Taking inspiration from prefix keys and prefix arguments, Transient implements a similar abstraction involving a prefix command, infix arguments and suffix commands. We could call this abstraction a “transient command”, but because it always involves at least two commands (a prefix and a suffix) we prefer to call it just a “transient”.
When the user calls a transient prefix command, a transient
(temporary) keymap is activated, which binds the transient’s infix
and suffix commands, and functions that control the transient state
are added to pre-command-hook and post-command-hook. The available
suffix and infix commands and their state are shown in a popup buffer
until the transient is exited by invoking a suffix command.
Calling an infix command causes its value to be changed, possibly by reading a new value in the minibuffer.
Calling a suffix command usually causes the transient to be exited but suffix commands can also be configured to not exit the transient.
The second part of this manual, which describes how to modify existing transients and create new transients from scratch, can be hard to digest if you are just getting started. A useful resource to get over that hurdle is Psionic K’s interactive tutorial, available at https://github.com/positron-solutions/transient-showcase.
This manual is for Transient version 0.4.3.
Copyright (C) 2018–2024 Free Software Foundation, Inc.
You can redistribute this document and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This document is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
Taking inspiration from prefix keys and prefix arguments, Transient implements a similar abstraction involving a prefix command, infix arguments and suffix commands. We could call this abstraction a “transient command”, but because it always involves at least two commands (a prefix and a suffix) we prefer to call it just a “transient”.
Transient keymaps are a feature provided by Emacs. Transients as implemented by this package involve the use of transient keymaps.
Emacs provides a feature that it calls prefix commands. When we talk about “prefix commands” in this manual, then we mean our own kind of “prefix commands”, unless specified otherwise. To avoid ambiguity we sometimes use the terms transient prefix command for our kind and “regular prefix command” for Emacs’ kind.
When the user calls a transient prefix command, a transient
(temporary) keymap is activated, which binds the transient’s infix and
suffix commands, and functions that control the transient state are
added to pre-command-hook and post-command-hook. The available suffix
and infix commands and their state are shown in a popup buffer until
the transient state is exited by invoking a suffix command.
Calling an infix command causes its value to be changed. How that is done depends on the type of the infix command. The simplest case is an infix command that represents a command-line argument that does not take a value. Invoking such an infix command causes the switch to be toggled on or off. More complex infix commands may read a value from the user, using the minibuffer.
Calling a suffix command usually causes the transient to be exited; the transient keymaps and hook functions are removed, the popup buffer no longer shows information about the (no longer bound) suffix commands, the values of some public global variables are set, while some internal global variables are unset, and finally the command is actually called. Suffix commands can also be configured to not exit the transient.
A suffix command can, but does not have to, use the infix arguments in
much the same way any command can choose to use or ignore the prefix
arguments. For a suffix command that was invoked from a transient, the
variable transient-current-suffixes and the function transient-args
serve about the same purpose as the variables prefix-arg and
current-prefix-arg do for any command that was called after the prefix
arguments have been set using a command such as universal-argument.
The information shown in the popup buffer while a transient is active looks a bit like this:
,----------------------------------------- |Arguments | -f Force (--force) | -a Annotate (--annotate) | |Create | t tag | r release `-----------------------------------------
This is a simplified version of
magit-tag. Info manuals do not support images or colored text, so the above “screenshot” lacks some information; in practice you would be able to tell whether the arguments--forceand--annotateare enabled or not based on their color.
Transient can be used to implement simple “command dispatchers”. The
main benefit then is that the user can see all the available commands
in a popup buffer. That is useful by itself because it frees the user
from having to remember all the keys that are valid after a certain
prefix key or command. Magit’s magit-dispatch (on C-x M-g) command is
an example of using Transient to merely implement a command
dispatcher.
In addition to that, Transient also allows users to interactively pass arguments to commands. These arguments can be much more complex than what is reasonable when using prefix arguments. There is a limit to how many aspects of a command can be controlled using prefix arguments. Furthermore, what a certain prefix argument means for different commands can be completely different, and users have to read documentation to learn and then commit to memory what a certain prefix argument means to a certain command.
Transient suffix commands, on the other hand, can accept dozens of different arguments without the user having to remember anything. When using Transient, one can call a command with arguments that are just as complex as when calling the same function non-interactively from Lisp.
Invoking a transient suffix command with arguments is similar to invoking a command in a shell with command-line completion and history enabled. One benefit of the Transient interface is that it remembers history not only on a global level (“this command was invoked using these arguments, and previously it was invoked using those other arguments”), but also remembers the values of individual arguments independently. See See Using History.
After a transient prefix command is invoked, C-h KEY can be used to show the documentation for the infix or suffix command that KEY is bound to (see Getting Help for Suffix Commands), and infixes and suffixes can be removed from the transient using C-x l KEY. Infixes and suffixes that are disabled by default can be enabled the same way. See Enabling and Disabling Suffixes.
Transient ships with support for a few different types of specialized infix commands. A command that sets a command line option, for example, has different needs than a command that merely toggles a boolean flag. Additionally, Transient provides abstractions for defining new types, which the author of Transient did not anticipate (or didn’t get around to implementing yet).
Note that suffix commands also support regular prefix arguments. A suffix command may even be called with both infix and prefix arguments at the same time. If you invoke a command as a suffix of a transient prefix command, but also want to pass prefix arguments to it, then first invoke the prefix command, and only after doing that invoke the prefix arguments, before finally invoking the suffix command. If you instead began by providing the prefix arguments, then those would apply to the prefix command, not the suffix command. Likewise, if you want to change infix arguments before invoking a suffix command with prefix arguments, then change the infix arguments before invoking the prefix arguments. In other words, regular prefix arguments always apply to the next command, and since transient prefix, infix and suffix commands are just regular commands, the same applies to them. (Regular prefix keys behave differently because they are not commands at all, instead they are just incomplete key sequences, and those cannot be interrupted with prefix commands.)
A transient prefix command is invoked like any other command by pressing the key that is bound to that command. The main difference to other commands is that a transient prefix command activates a transient keymap, which temporarily binds the transient’s infix and suffix commands. Bindings from other keymaps may, or may not, be disabled while the transient state is in effect.
There are two kinds of commands that are available after invoking a transient prefix command; infix and suffix commands. Infix commands set some value (which is then shown in a popup buffer), without leaving the transient. Suffix commands, on the other hand, usually quit the transient and they may use the values set by the infix commands, i.e., the infix arguments.
Instead of setting arguments to be used by a suffix command, infix commands may also set some value by side-effect, e.g., by setting the value of some variable.
To quit the transient without invoking a suffix command press C-g.
Key bindings in transient keymaps may be longer than a single event. After pressing a valid prefix key, all commands whose bindings do not begin with that prefix key are temporarily unavailable and grayed out. To abort the prefix key press C-g (which in this case only quits the prefix key, but not the complete transient).
A transient prefix command can be bound as a suffix of another transient. Invoking such a suffix replaces the current transient state with a new transient state, i.e., the available bindings change and the information displayed in the popup buffer is updated accordingly. Pressing C-g while a nested transient is active only quits the innermost transient, causing a return to the previous transient.
C-q or C-z on the other hand always exits all transients. If you use the latter, then you can later resume the stack of transients using M-x transient-resume.
transient-quit-seq) ¶transient-quit-one)This key quits the currently active incomplete key sequence, if any, or else the current transient. When quitting the current transient, it returns to the previous transient, if any.
Transient’s predecessor bound q instead of C-g to the quit command.
To learn how to get that binding back see transient-bind-q-to-quit’s
doc string.
transient-quit-all) ¶This command quits the currently active incomplete key sequence, if any, and all transients, including the active transient and all suspended transients, if any.
transient-suspend) ¶Like transient-quit-all, this command quits an incomplete key
sequence, if any, and all transients. Additionally, it saves the
stack of transients so that it can easily be resumed (which is
particularly useful if you quickly need to do “something else” and
the stack is deeper than a single transient, and/or you have already
changed the values of some infix arguments).
Note that only a single stack of transients can be saved at a time. If another stack is already saved, then saving a new stack discards the previous stack.
This command resumes the previously suspended stack of transients, if any.
A few shared suffix commands are available in all transients. These suffix commands are not shown in the popup buffer by default.
This includes the aborting commands mentioned in the previous section, as well as some other commands that are all bound to C-x KEY. After C-x is pressed, a section featuring all these common commands is temporarily shown in the popup buffer. After invoking one of them, the section disappears again. Note, however, that one of these commands is described as “Show common permanently”; invoke that if you want the common commands to always be shown for all transients.
transient-toggle-common) ¶This command toggles whether the generic commands that are common to all transients are always displayed or only after typing the incomplete prefix key sequence C-x. This only affects the current Emacs session.
This option controls whether shared suffix commands are shown alongside the transient-specific infix and suffix commands. By default, the shared commands are not shown to avoid overwhelming the user with too many options.
While a transient is active, pressing C-x always shows the common commands. The value of this option can be changed for the current Emacs session by typing C-x t while a transient is active.
The other common commands are described in either the previous or in one of the following sections.
Some of Transient’s key bindings differ from the respective bindings of Magit-Popup; see FAQ for more information.
After setting the infix arguments in a transient, the user can save those arguments for future invocations.
Most transients will start out with the saved arguments when they are invoked. There are a few exceptions, though. Some transients are designed so that the value that they use is stored externally as the buffer-local value of some variable. Invoking such a transient again uses the buffer-local value. 1
If the user does not save the value and just exits using a regular suffix command, then the value is merely saved to the transient’s history. That value won’t be used when the transient is next invoked, but it is easily accessible (see Using History).
transient-set) ¶This command saves the value of the active transient for this Emacs session.
transient-save) ¶Save the value of the active transient persistently across Emacs sessions.
transient-reset) ¶Clear the set and saved values of the active transient.
This option names the file that is used to persist the values of transients between Emacs sessions.
Every time the user invokes a suffix command the transient’s current value is saved to its history. These values can be cycled through the same way one can cycle through the history of commands that read user-input in the minibuffer.
transient-history-prev) ¶This command switches to the previous value used for the active transient.
transient-history-next) ¶This command switches to the next value used for the active transient.
In addition to the transient-wide history, Transient of course supports per-infix history. When an infix reads user-input using the minibuffer, the user can use the regular minibuffer history commands to cycle through previously used values. Usually the same keys as those mentioned above are bound to those commands.
Authors of transients should arrange for different infix commands that read the same kind of value to also use the same history key (see Suffix Slots).
Both kinds of history are saved to a file when Emacs is exited.
This option names the file that is used to persist the history of transients and their infixes between Emacs sessions.
This option controls how many history elements are kept at the time
the history is saved in transient-history-file.
Transients can have many suffixes and infixes that the user might not be familiar with. To make it trivial to get help for these, Transient provides access to the documentation directly from the active transient.
transient-help) ¶This command enters help mode. When help mode is active, typing a key shows information about the suffix command that the key normally is bound to (instead of invoking it). Pressing C-h a second time shows information about the prefix command.
After typing a key, the stack of transient states is suspended and information about the suffix command is shown instead. Typing q in the help buffer buries that buffer and resumes the transient state.
What sort of documentation is shown depends on how the transient was
defined. For infix commands that represent command-line arguments
this ideally shows the appropriate manpage. transient-help then tries
to jump to the correct location within that. Info manuals are also
supported. The fallback is to show the command’s doc string, for
non-infix suffixes this is usually appropriate.
The user base of a package that uses transients can be very diverse. This is certainly the case for Magit; some users have been using it and Git for a decade, while others are just getting started now.
For that reason a mechanism is needed that authors can use to classify a transient’s infixes and suffixes along the essentials…everything spectrum. We use the term levels to describe that mechanism.
Each suffix command is placed on a level and each transient has a level (called transient-level), which controls which suffix commands are available. Integers between 1 and 7 (inclusive) are valid levels. For suffixes, 0 is also valid; it means that the suffix is not displayed at any level.
The levels of individual transients and/or their individual suffixes can be changed interactively, by invoking the transient and then pressing C-x l to enter the “edit” mode, see below.
The default level for both transients and their suffixes is 4. The
transient-default-level option only controls the default for
transients. The default suffix level is always 4. The authors of
transients should place certain suffixes on a higher level, if they
expect that it won’t be of use to most users, and they should place
very important suffixes on a lower level, so that they remain
available even if the user lowers the transient level.
This option controls which suffix levels are made available by default. It sets the transient-level for transients for which the user has not set that individually.
This option names the file that is used to persist the levels of transients and their suffixes between Emacs sessions.
transient-set-level) ¶This command enters edit mode. When edit mode is active, then all infixes and suffixes that are currently usable are displayed along with their levels. The colors of the levels indicate whether they are enabled or not. The level of the transient is also displayed along with some usage information.
In edit mode, pressing the key that would usually invoke a certain suffix instead prompts the user for the level that suffix should be placed on.
Help mode is available in edit mode.
To change the transient level press C-x l again.
To exit edit mode press C-g.
Note that edit mode does not display any suffixes that are not
currently usable. magit-rebase, for example, shows different
suffixes depending on whether a rebase is already in progress or
not. The predicates also apply in edit mode.
Therefore, to control which suffixes are available given a certain state, you have to make sure that that state is currently active.
When invoking a transient in a small frame, the transient window may
not show the complete buffer, making it necessary to scroll, using the
following commands. These commands are never shown in the transient
window, and the key bindings are the same as for scroll-up-command and
scroll-down-command in other buffers.
This command scrolls text of transient popup window upward ARG
lines. If ARG is nil, then it scrolls near full screen. This
is a wrapper around scroll-up-command (which see).
This command scrolls text of transient popup window down ARG
lines. If ARG is nil, then it scrolls near full screen. This
is a wrapper around scroll-down-command (which see).
More options are described in Common Suffix Commands, in Saving Values, in Using History and in Enabling and Disabling Suffixes.
Also see Common Suffix Commands.
This option controls whether the current transient’s infix and suffix commands are shown in the popup buffer.
t (the default) then the popup buffer is shown as soon as a
transient prefix command is invoked.
nil, then the popup buffer is not shown unless the user
explicitly requests it, by pressing an incomplete prefix key
sequence.
The popup is shown when the user explicitly requests it by pressing an incomplete prefix key sequence. Unless this is zero, the popup is shown after that many seconds of inactivity (using the absolute value).
This option controls whether navigation commands are enabled in the transient popup buffer.
While a transient is active the transient popup buffer is not the
current buffer, making it necessary to use dedicated commands to act
on that buffer itself. This is disabled by default. If this option
is non-nil, then the following features are available:
This option specifies the action used to display the transient popup
buffer. The transient popup buffer is displayed in a window using
(display-buffer BUFFER transient-display-buffer-action).
The value of this option has the form (FUNCTION . ALIST),
where FUNCTION is a function or a list of functions. Each such
function should accept two arguments: a buffer to display and an
alist of the same form as ALIST. See (elisp)Choosing Window,
for details.
The default is:
(display-buffer-in-side-window (side . bottom) (inhibit-same-window . t) (window-parameters (no-other-window . t)))
This displays the window at the bottom of the selected frame.
Another useful FUNCTION is display-buffer-below-selected, which
is what magit-popup used by default. For more alternatives see
(elisp)Buffer Display Action Functions, and see (elisp)Buffer Display
Action Alists.
Note that the buffer that was current before the transient buffer
is shown should remain the current buffer. Many suffix commands
act on the thing at point, if appropriate, and if the transient
buffer became the current buffer, then that would change what is
at point. To that effect inhibit-same-window ensures that the
selected window is not used to show the transient buffer.
It may be possible to display the window in another frame, but whether that works in practice depends on the window-manager. If the window manager selects the new window (Emacs frame), then that unfortunately changes which buffer is current.
If you change the value of this option, then you might also
want to change the value of transient-mode-line-format.
This option controls whether the use of a single column to display suffixes is enforced. This might be useful for users with low vision who use large text and might otherwise have to scroll in two dimensions.
This option controls whether the transient popup buffer has a mode-line, separator line, or neither.
If nil, then the buffer has no mode-line. If the buffer is not
displayed right above the echo area, then this probably is not a
good value.
If line (the default), then the buffer also has no mode-line, but a
thin line is drawn instead, using the background color of the face
transient-separator. Text-mode frames cannot display thin lines,
and therefore fall back to treating line like nil.
Otherwise this can be any mode-line format. See (elisp)Mode Line Format, for details.
This option controls whether prefixes and suffixes are colored in a Hydra-like fashion.
If non-nil, then the key binding of each suffix is colorized to
indicate whether it exits the transient state or not. The color of
the prefix is indicated using the line that is drawn when the value
of transient-mode-line-format is line.
For more information about how Hydra uses colors see https://github.com/abo-abo/hydra#color and https://oremacs.com/2015/02/19/hydra-colors-reloaded.
This option controls whether key bindings of infix commands that do not match the respective command-line argument should be highlighted. For other infix commands this option has no effect.
When this option is non-nil, the key binding for an infix argument
is highlighted when only a long argument (e.g., --verbose) is
specified but no shorthand (e.g., -v). In the rare case that a
shorthand is specified but the key binding does not match, then it
is highlighted differently.
Highlighting mismatched key bindings is useful when learning the arguments of the underlying command-line tool; you wouldn’t want to learn any short-hands that do not actually exist.
The highlighting is done using one of the faces
transient-mismatched-key and transient-nonstandard-key.
This function is used to modify key bindings. If the value of this
option is nil (the default), then no substitution is performed.
This function is called with one argument, the prefix object, and
must return a key binding description, either the existing key
description it finds in the key slot, or the key description that
replaces the prefix key. It could be used to make other
substitutions, but that is discouraged.
For example, = is hard to reach using my custom keyboard layout, so I substitute ( for that, which is easy to reach using a layout optimized for lisp.
(setq transient-substitute-key-function
(lambda (obj)
(let ((key (oref obj key)))
(if (string-match "\\`\\(=\\)[a-zA-Z]" key)
(replace-match "(" t t key 1)
key))))
This option controls whether the last history element is used as the
initial minibuffer input when reading the value of an infix argument
from the user. If nil, there is no initial input and the first
element has to be accessed the same way as the older elements.
This option controls whether the transient buffer is hidden while user input is being read in the minibuffer.
This option controls whether columns are aligned pixel-wise in the popup buffer.
If this is non-nil, then columns are aligned pixel-wise to support
variable-pitch fonts. Keys are not aligned, so you should use a
fixed-pitch font for the transient-key face. Other key faces
inherit from that face unless a theme is used that breaks that
relationship.
This option is intended for users who use a variable-pitch font for
the default face.
This option controls whether to force the use of a monospaced font
in popup buffer. Even if you use a proportional font for the
default face, you might still want to use a monospaced font in
transient’s popup buffer. Setting this option to t causes default
to be remapped to fixed-pitch in that buffer.
These options are mainly intended for developers.
This option controls whether key binding conflicts should be detected at the time the transient is invoked. If so, this results in an error, which prevents the transient from being used. Because of that, conflicts are ignored by default.
Conflicts cannot be determined earlier, i.e., when the transient is being defined and when new suffixes are being added, because at that time there can be false-positives. It is actually valid for multiple suffixes to share a common key binding, provided the predicates of those suffixes prevent that more than one of them is enabled at a time.
This option controls whether suffixes that would not be available by default are highlighted.
When non-nil then the descriptions of suffixes are highlighted if
their level is above 4, the default of transient-default-level.
Assuming you have set that variable to 7, this highlights all
suffixes that won’t be available to users without them making the
same customization.
To an extent, transients can be customized interactively, see Enabling and Disabling Suffixes. This section explains how existing transients can be further modified non-interactively. Let’s begin with an example:
(transient-append-suffix 'magit-patch-apply "-3"
'("-R" "Apply in reverse" "--reverse"))
This inserts a new infix argument to toggle the --reverse argument
after the infix argument that toggles -3 in magit-patch-apply.
The following functions share a few arguments:
transient-define-prefix. Note that an infix is a
special kind of suffix. Depending on context “suffixes” means
“suffixes (including infixes)” or “non-infix suffixes”. Here it
means the former. See Suffix Specifications.
SUFFIX may also be a group in the same form as expected by
transient-define-prefix. See Group Specifications.
key-description), or a list specifying coordinates (the
last element may also be a command or key). For example (1 0 -1)
identifies the last suffix (-1) of the first subgroup (0) of the
second group (1).
If LOC is a list of coordinates, then it can be used to identify a group, not just an individual suffix command.
The function transient-get-suffix can be useful to determine whether
a certain coordination list identifies the suffix or group that you
expect it to identify. In hairy cases it may be necessary to look
at the definition of the transient prefix command.
These functions operate on the information stored in the
transient--layout property of the PREFIX symbol. Suffix entries in
that tree are not objects but have the form (LEVEL CLASS PLIST), where
PLIST should set at least :key, :description and :command.
These functions insert the suffix or group SUFFIX into PREFIX before or after LOC.
Conceptually adding a binding to a transient prefix is similar to adding a binding to a keymap, but this is complicated by the fact that multiple suffix commands can be bound to the same key, provided they are never active at the same time, see Predicate Slots.
Unfortunately both false-positives and false-negatives are possible.
To deal with the former use non-nil KEEP-OTHER. To deal with the
latter remove the conflicting binding explicitly.
This function replaces the suffix or group at LOC in PREFIX with suffix or group SUFFIX.
This function removes the suffix or group at LOC in PREFIX.
This function returns the suffix or group at LOC in PREFIX. The returned value has the form mentioned above.
This function edits the suffix or group at LOC in PREFIX, by setting the PROP of its plist to VALUE.
Most of these functions do not signal an error if they cannot perform
the requested modification. The functions that insert new suffixes
show a warning if LOC cannot be found in PREFIX without signaling an
error. The reason for doing it like this is that establishing a key
binding (and that is what we essentially are trying to do here) should
not prevent the rest of the configuration from loading. Among these
functions only transient-get-suffix and transient-suffix-put may
signal an error.
A transient consists of a prefix command and at least one suffix command, though usually a transient has several infix and suffix commands. The below macro defines the transient prefix command and binds the transient’s infix and suffix commands. In other words, it defines the complete transient, not just the transient prefix command that is used to invoke that transient.
This macro defines NAME as a transient prefix command and binds the transient’s infix and suffix commands.
ARGLIST are the arguments that the prefix command takes. DOCSTRING is the documentation string and is optional.
These arguments can optionally be followed by keyword-value pairs.
Each key has to be a keyword symbol, either :class or a keyword
argument supported by the constructor of that class. The
transient-prefix class is used if the class is not specified
explicitly.
GROUPs add key bindings for infix and suffix commands and specify how these bindings are presented in the popup buffer. At least one GROUP has to be specified. See Binding Suffix and Infix Commands.
The BODY is optional. If it is omitted, then ARGLIST is ignored and the function definition becomes:
(lambda () (interactive) (transient-setup 'NAME))
If BODY is specified, then it must begin with an interactive form
that matches ARGLIST, and it must call transient-setup. It may,
however, call that function only when some condition is satisfied.
All transients have a (possibly nil) value, which is exported when
suffix commands are called, so that they can consume that value.
For some transients it might be necessary to have a sort of
secondary value, called a “scope”. Such a scope would usually be
set in the command’s interactive form and has to be passed to the
setup function:
(transient-setup 'NAME nil nil :scope SCOPE)
For example, the scope of the magit-branch-configure transient is
the branch whose variables are being configured.
The macro transient-define-prefix is used to define a transient.
This defines the actual transient prefix command (see Defining Transients) and adds the transient’s infix and suffix bindings, as
described below.
Users and third-party packages can add additional bindings using
functions such as transient-insert-suffix (see Modifying Existing Transients). These functions take a “suffix
specification” as one of their arguments, which has the same form as
the specifications used in transient-define-prefix.
The suffix and infix commands of a transient are organized in groups. The grouping controls how the descriptions of the suffixes are outlined visually but also makes it possible to set certain properties for a set of suffixes.
Several group classes exist, some of which organize suffixes in subgroups. In most cases the class does not have to be specified explicitly, but see Group Classes.
Groups are specified in the call to transient-define-prefix, using
vectors. Because groups are represented using vectors, we cannot use
square brackets to indicate an optional element and instead use curly
brackets to do the latter.
Group specifications then have this form:
[{LEVEL} {DESCRIPTION}
{KEYWORD VALUE}...
ELEMENT...]
The LEVEL is optional and defaults to 4. See Enabling and Disabling Suffixes.
The DESCRIPTION is optional. If present, it is used as the heading of the group.
The KEYWORD-VALUE pairs are optional. Each keyword has to be a
keyword symbol, either :class or a keyword argument supported by the
constructor of that class.
:description, is equivalent to specifying
DESCRIPTION at the very beginning of the vector. The recommendation
is to use :description if some other keyword is also used, for
consistency, or DESCRIPTION otherwise, because it looks better.
:level is equivalent to LEVEL.
:if... keywords. These
keywords control whether the group is available in a certain
situation.
For example, one group of the magit-rebase transient uses :if
magit-rebase-in-progress-p, which contains the suffixes that are
useful while rebase is already in progress; and another that uses
:if-not magit-rebase-in-progress-p, which contains the suffixes that
initiate a rebase.
These predicates can also be used on individual suffixes and are only documented once, see Predicate Slots.
:hide, if non-nil, is a predicate that controls
whether the group is hidden by default. The key bindings for
suffixes of a hidden group should all use the same prefix key.
Pressing that prefix key should temporarily show the group and its
suffixes, which assumes that a predicate like this is used:
(lambda ()
(eq (car transient--redisplay-key)
?\C-c)) ; the prefix key shared by all bindings
:setup-children, if non-nil, is a function that takes
one argument, a potentially list of children, and must return a list
of children or an empty list. This can either be used to somehow
transform the group’s children that were defined the normal way, or
to dynamically create the children from scratch.
The returned children must have the same form as stored in the
prefix’s transient--layout property, but it is often more convenient
to use the same form as understood by transient-define-prefix,
described below. If you use the latter approach, you can use the
transient-parse-child and transient-parse-children functions to
transform them from the convenient to the expected form.
:pad-keys argument controls whether keys of all suffixes
contained in a group are right padded, effectively aligning the
descriptions.
The ELEMENTs are either all subgroups, or all suffixes and strings. (At least currently no group type exists that would allow mixing subgroups with commands at the same level, though in principle there is nothing that prevents that.)
If the ELEMENTs are not subgroups, then they can be a mixture of lists that specify commands and strings. Strings are inserted verbatim into the buffer. The empty string can be used to insert gaps between suffixes, which is particularly useful if the suffixes are outlined as a table.
Inside group specifications, including inside contained suffix
specifications, nothing has to be quoted and quoting anyway is
invalid. The value following a keyword, can be explicitly unquoted
using ,. This feature is experimental and should be avoided.
The form of suffix specifications is documented in the next node.
A transient’s suffix and infix commands are bound when the transient
prefix command is defined using transient-define-prefix, see
Defining Transients. The commands are organized into groups, see
Group Specifications. Here we describe the form used to bind an
individual suffix command.
The same form is also used when later binding additional commands
using functions such as transient-insert-suffix, see Modifying Existing Transients.
Note that an infix is a special kind of suffix. Depending on context “suffixes” means “suffixes (including infixes)” or “non-infix suffixes”. Here it means the former.
Suffix specifications have this form:
([LEVEL] [KEY [DESCRIPTION]] COMMAND|ARGUMENT [KEYWORD VALUE]...)
LEVEL, KEY and DESCRIPTION can also be specified using the KEYWORDs
:level, :key and :description. If the object that is associated with
COMMAND sets these properties, then they do not have to be specified
here. You can however specify them here anyway, possibly overriding
the object’s values just for the binding inside this transient.
:description in that
case.
The next element is either a command or an argument. This is the only argument that is mandatory in all cases.
Any command will do; it does not need to have an object associated
with it (as would be the case if transient-define-suffix or
transient-define-infix were used to define it).
COMMAND can also be a lambda expression.
As mentioned above, the object that is associated with a command can be used to set the default for certain values that otherwise have to be set in the suffix specification. Therefore if there is no object, then you have to make sure to specify the KEY and the DESCRIPTION.
As a special case, if you want to add a command that might be neither defined nor autoloaded, you can use a workaround like:
(transient-insert-suffix 'some-prefix "k"
'("!" "Ceci n'est pas une commande" no-command
:if (lambda () (featurep 'no-library))))
Instead of featurep you could also use require with a non-nil value
for NOERROR.
Instead of a string, this can also be a list of two strings, in
which case the first string is used as the short argument (which can
also be specified using :shortarg) and the second as the long argument
(which can also be specified using :argument).
Only the long argument is displayed in the popup buffer. See
transient-detect-key-conflicts for how the short argument may be
used.
Unless the class is specified explicitly, the appropriate class is
guessed based on the long argument. If the argument ends with ‘=’
(e.g., ‘--format=’) then transient-option is used, otherwise
transient-switch.
Finally, details can be specified using optional KEYWORD-VALUE pairs.
Each keyword has to be a keyword symbol, either :class or a keyword
argument supported by the constructor of that class. See Suffix Slots.
Note that an infix is a special kind of suffix. Depending on context “suffixes” means “suffixes (including infixes)” or “non-infix suffixes”.
This macro defines NAME as a transient suffix command.
ARGLIST are the arguments that the command takes. DOCSTRING is the documentation string and is optional.
These arguments can optionally be followed by keyword-value pairs.
Each keyword has to be a keyword symbol, either :class or a keyword
argument supported by the constructor of that class. The
transient-suffix class is used if the class is not specified
explicitly.
The BODY must begin with an interactive form that matches ARGLIST.
The infix arguments are usually accessed by using transient-args
inside interactive.
This macro defines NAME as a transient infix command.
ARGLIST is always ignored (but mandatory never-the-less) and reserved for future use. DOCSTRING is the documentation string and is optional.
The keyword-value pairs are mandatory. All transient infix commands
are equal to each other (but not eq), so it is meaningless to define
an infix command without also setting at least :class and one other
keyword (which it is depends on the used class, usually :argument or
:variable).
Each keyword has to be a keyword symbol, either :class or a keyword
argument supported by the constructor of that class. The
transient-switch class is used if the class is not specified
explicitly.
The function definition is always:
(lambda ()
(interactive)
(let ((obj (transient-suffix-object)))
(transient-infix-set obj (transient-infix-read obj)))
(transient--show))
transient-infix-read and transient-infix-set are generic functions.
Different infix commands behave differently because the concrete
methods are different for different infix command classes. In rare
cases the above command function might not be suitable, even if you
define your own infix command class. In that case you have to use
transient-define-suffix to define the infix command and use t as the
value of the :transient keyword.
This macro defines NAME as a transient infix command.
This is an alias for transient-define-infix. Only use this alias
to define an infix command that actually sets an infix argument.
To define an infix command that, for example, sets a variable, use
transient-define-infix instead.
The functions and the variables described below allow suffix commands to access the value of the transient from which they were invoked; which is the value of its infix arguments. These variables are set when the user invokes a suffix command that exits the transient, but before actually calling the command.
When returning to the command-loop after calling the suffix command,
the arguments are reset to nil (which causes the function to return
nil too).
Like for Emacs’ prefix arguments, it is advisable, but not mandatory,
to access the infix arguments inside the command’s interactive form.
The preferred way of doing that is to call the transient-args
function, which for infix arguments serves about the same purpose as
prefix-arg serves for prefix arguments.
This function returns the value of the transient prefix command PREFIX.
If the current command was invoked from the transient prefix command PREFIX, then it returns the active infix arguments. If the current command was not invoked from PREFIX, then it returns the set, saved or default value for PREFIX.
This function return the value of ARG as it appears in ARGS.
For a switch a boolean is returned. For an option the value is
returned as a string, using the empty string for the empty value,
or nil if the option does not appear in ARGS.
This function returns the suffixes of the transient prefix command PREFIX. This is a list of objects. This function should only be used if you need the objects (as opposed to just their values) and if the current command is not being invoked from PREFIX.
The suffixes of the transient from which this suffix command was
invoked. This is a list of objects. Usually it is sufficient to
instead use the function transient-args, which returns a list of
values. In complex cases it might be necessary to use this variable
instead, i.e., if you need access to information beside the value.
The transient from which this suffix command was invoked. The
returned value is a transient-prefix object, which holds information
associated with the transient prefix command.
The transient from which this suffix command was invoked. The returned value is a symbol, the transient prefix command.
Invoking a transient prefix command “activates” the respective transient, i.e., it puts a transient keymap into effect, which binds the transient’s infix and suffix commands.
The default behavior while a transient is active is as follows:
But these are just the defaults. Whether a certain command deactivates or “exits” the transient is configurable. There is more than one way in which a command can be “transient” or “non-transient”; the exact behavior is implemented by calling a so-called “pre-command” function. Whether non-suffix commands are allowed to be called is configurable per transient.
transient slot, which can be set
either when defining the command or when adding a binding to a
transient while defining the respective transient prefix command.
Valid values are booleans and the pre-commands described below.
t is equivalent to transient--do-stay.
nil is equivalent to transient--do-exit.
transient is unbound (and that is actually the default for
non-infix suffixes) then the value of the prefix’s
transient-suffix slot is used instead. The default value of that
slot is nil, so the suffix’s transient slot being unbound is
essentially equivalent to it being nil.
For transient-suffix objects the transient slot is unbound. We can
ignore that for the most part because, as stated above, nil and the
slot being unbound are equivalent, and mean “do exit”. That isn’t
actually true for suffixes that are sub-prefixes though. For such
suffixes unbound means “do exit but allow going back”, which is the
default, while nil means “do exit permanently”, which requires that
slot to be explicitly set to that value.
transient-predicate-map. This is a special keymap, which
binds commands to pre-commands (as opposed to keys to commands) and
takes precedence over the transient slot.
The available pre-command functions are documented below. They are
called by transient--pre-command, a function on pre-command-hook and
the value that they return determines whether the transient is exited.
To do so the value of one of the constants transient--exit or
transient--stay is used (that way we don’t have to remember if t means
“exit” or “stay”).
Additionally, these functions may change the value of this-command
(which explains why they have to be called using pre-command-hook),
call transient-export, transient--stack-zap or transient--stack-push;
and set the values of transient--exitp, transient--helpp or
transient--editp.
The default for infixes is transient--do-stay. This is also the only
function that makes sense for infixes.
Call the command without exporting variables and stay transient.
By default, invoking a suffix causes the transient to be exited.
If you want a different default behavior for a certain transient
prefix command, then set its :transient-suffix slot. The value can be
a boolean, answering the question "does the transient stay active,
when a suffix command is invoked?" t means that the transient stays
active, while nil means that invoking a suffix exits the transient.
In either case, the exact behavior depends on whether the suffix is
itself a prefix (i.e., a sub-prefix), an infix or a regular suffix.
The behavior for an individual suffix command can be changed by
setting its transient slot to one of the following pre-commands.
Call the command after exporting variables and exit the transient.
Call the command after exporting variables and return to parent
prefix. If there is no parent prefix, then call transient--do-exit.
Call the command after exporting variables and stay transient.
The following pre-commands are suitable for sub-prefixes. Only the
first should ever explicitly be set as the value of the transient
slot.
Call the transient prefix command, preparing for return to active transient.
Whether we actually return to the parent transient is ultimately
under the control of each invoked suffix. The difference between
this pre-command and transient--do-replace is that it changes the
value of the transient-suffix slot to transient--do-return.
If there is no parent transient, then only call this command and skip the second step.
Call the transient prefix command, replacing the active transient.
Unless transient--do-recurse is explicitly used, this pre-command
is automatically used for suffixes that are prefixes themselves,
i.e., for sub-prefixes.
Suspend the active transient, saving the transient stack.
This is used by the command transient-suspend and optionally also by
“external events” such as handle-switch-frame. Such bindings should
be added to transient-predicate-map.
By default, non-suffixes (commands that are bound in other keymaps beside the transient keymap) cannot be invoked. Trying to invoke such a command results in a warning and the transient stays active.
If you want a different behavior, then set the :transient-non-suffix
slot of the transient prefix command. The value can be a boolean,
answering the question, "is it allowed to invoke non-suffix commands?"
If the value is t or transient--do-stay, then non-suffixes can be
invoked, when it is nil or transient--do-warn (the default) then they
cannot be invoked.
The only other recommended value is transient--do-leave. If that is
used, then non-suffixes can be invoked, but if one is invoked, then
that exits the transient.
Call transient-undefined and stay transient.
Call the command without exporting variables and stay transient.
Call the command without exporting variables and exit the transient.
If active, quit help or edit mode, else exit the active transient.
This is used when the user pressed C-g.
Exit all transients without saving the transient stack.
This is used when the user pressed C-q.
Suspend the active transient, saving the transient stack.
This is used when the user pressed C-z.
Transient uses classes and generic functions to make it possible to define new types of suffix commands that are similar to existing types, but behave differently in some aspects. It does the same for groups and prefix commands, though at least for prefix commands that currently appears to be less important.
Every prefix, infix and suffix command is associated with an object, which holds information that controls certain aspects of its behavior. This happens in two ways.
That in turn makes it possible for third-parties to add new types without having to convince the maintainer of Transient that that new type is important enough to justify adding a special case to a dozen or so functions.
Two commands may have the same type, but obviously their key bindings and descriptions still have to be different, for example.
The values of some slots are functions. The reader slot for example
holds a function that is used to read a new value for an infix
command. The values of such slots are regular functions.
Generic functions are used when a function should do something different based on the type of the command, i.e., when all commands of a certain type should behave the same way but different from the behavior for other types. Object slots that hold a regular function as value are used when the task that they perform is likely to differ even between different commands of the same type.
The type of a group can be specified using the :class property at the
beginning of the class specification, e.g., [:class transient-columns
...] in a call to transient-define-prefix.
transient-child class is the base class of both
transient-group (and therefore all groups) as well as of
transient-suffix (and therefore all suffix and infix commands).
This class exists because the elements (or “children”) of certain groups can be other groups instead of suffix and infix commands.
transient-group class is the superclass of all other
group classes.
transient-column class is the simplest group.
This is the default “flat” group. If the class is not specified explicitly and the first element is not a vector (i.e., not a group), then this class is used.
This class displays each element on a separate line.
transient-row class displays all elements on a single line.
transient-columns class displays commands organized in columns.
Direct elements have to be groups whose elements have to be commands or strings. Each subgroup represents a column. This class takes care of inserting the subgroups’ elements.
This is the default “nested” group. If the class is not specified explicitly and the first element is a vector (i.e., a group), then this class is used.
transient-subgroups class wraps other groups.
Direct elements have to be groups whose elements have to be commands or strings. This group inserts an empty line between subgroups. The subgroups themselves are responsible for displaying their elements.
This generic function can be used to setup the children or a group.
The default implementation usually just returns the children
unchanged, but if the setup-children slot of GROUP is non-nil, then
it calls that function with CHILDREN as the only argument and
returns the value.
The children are given as a (potentially empty) list consisting of either group or suffix specifications. These functions can make arbitrary changes to the children including constructing new children from scratch.
This generic function formats the group and its elements and inserts the result into the current buffer, which is a temporary buffer. The contents of that buffer are later inserted into the popup buffer.
Functions that are called by this function may need to operate in
the buffer from which the transient was called. To do so they can
temporarily make the transient--source-buffer the current buffer.
Currently the transient-prefix class is being used for all prefix
commands and there is only a single generic function that can be
specialized based on the class of a prefix command.
This generic function is called while setting up the transient and
is responsible for initializing the history slot. This is the
transient-wide history; many individual infixes also have a history
of their own.
The default (and currently only) method extracts the value from the
global variable transient-history.
A transient prefix command’s object is stored in the transient--prefix
property of the command symbol. While a transient is active, a clone
of that object is stored in the variable transient--prefix. A clone
is used because some changes that are made to the active transient’s
object should not affect later invocations.
transient-suffix, which in
turn derives from transient-child, from which transient-group also
derives (see Group Classes).
transient-infix class,
which in turn derives from the transient-suffix class.
Infixes are a special type of suffixes. The primary difference is
that infixes always use the transient--do-stay pre-command, while
non-infix suffixes use a variety of pre-commands (see Transient State). Doing that is most easily achieved by using this class,
though theoretically it would be possible to define an infix class
that does not do so. If you do that then you get to implement many
methods.
Also, infixes and non-infix suffixes are usually defined using different macros (see Defining Suffix and Infix Commands).
transient-argument class.
transient-switch class (or a derived class) is used for infix
arguments that represent command-line switches (arguments that do
not take a value).
transient-option class (or a derived class) is used for infix
arguments that represent command-line options (arguments that do
take a value).
transient-switches class can be used for a set of mutually
exclusive command-line switches.
transient-files class can be used for a ‘--’ argument that
indicates that all remaining arguments are files.
transient-variable class.
Magit defines additional classes, which can serve as examples for the fancy things you can do without modifying Transient. Some of these classes will likely get generalized and added to Transient. For now they are very much subject to change and not documented.
To get information about the methods implementing these generic
functions use describe-function.
This generic function sets the initial value of the object OBJ.
This function is called for all suffix commands, but unless a
concrete method is implemented this falls through to the default
implementation, which is a noop. In other words this usually
only does something for infix commands, but note that this is
not implemented for the abstract class transient-infix, so if
your class derives from that directly, then you must implement
a method.
This generic function determines the new value of the infix object OBJ.
This function merely determines the value; transient-infix-set is
used to actually store the new value in the object.
For most infix classes this is done by reading a value from the
user using the reader specified by the reader slot (using the
transient-infix-value method described below).
For some infix classes the value is changed without reading anything in the minibuffer, i.e., the mere act of invoking the infix command determines what the new value should be, based on the previous value.
This generic function returns the prompt to be used to read infix object OBJ’s value.
This generic function sets the value of infix object OBJ to VALUE.
This generic function returns the value of the suffix object OBJ.
This function is called by transient-args (which see), meaning this
function is how the value of a transient is determined so that the
invoked suffix command can use it.
Currently most values are strings, but that is not set in stone.
nil is not a value, it means “no value”.
Usually only infixes have a value, but see the method for
transient-suffix.
This generic function sets the scope of the suffix object OBJ.
The scope is actually a property of the transient prefix, not of
individual suffixes. However it is possible to invoke a suffix
command directly instead of from a transient. In that case, if
the suffix expects a scope, then it has to determine that itself
and store it in its scope slot.
This function is called for all suffix commands, but unless a concrete method is implemented this falls through to the default implementation, which is a noop.
This generic function formats and returns OBJ for display.
When this function is called, then the current buffer is some
temporary buffer. If you need the buffer from which the prefix
command was invoked to be current, then do so by temporarily
making transient--source-buffer current.
This generic function formats OBJ’s key for display and returns the
result.
This generic function formats OBJ’s description for display and
returns the result.
This generic function formats OBJ’s value for display and returns the result.
Show help for the prefix, infix or suffix command represented by OBJ.
For prefixes, show the info manual, if that is specified using the
info-manual slot. Otherwise, show the manpage if that is specified
using the man-page slot. Otherwise, show the command’s doc string.
For suffixes, show the command’s doc string.
For infixes, show the manpage if that is specified. Otherwise show the command’s doc string.
show-help, man-page or info-manual can be used to specify the
documentation for the prefix and its suffixes. The command
transient-help uses the method transient-show-help (which see) to
lookup and use these values.
history-key If multiple prefix commands should share a single value,
then this slot has to be set to the same value for all of them. You
probably don’t want that.
transient-suffix and transient-non-suffix play a part when
determining whether the currently active transient prefix command
remains active/transient when a suffix or arbitrary non-suffix
command is invoked. See Transient State.
incompatible A list of lists. Each sub-list specifies a set of
mutually exclusive arguments. Enabling one of these arguments
causes the others to be disabled. An argument may appear in
multiple sub-lists.
scope For some transients it might be necessary to have a sort of
secondary value, called a “scope”. See transient-define-prefix.
These slots are mostly intended for internal use. They should not be
set in calls to transient-define-prefix.
prototype When a transient prefix command is invoked, then a clone
of that object is stored in the global variable transient--prefix
and the prototype is stored in the clone’s prototype slot.
command The command, a symbol. Each transient prefix command
consists of a command, which is stored in a symbol’s function slot
and an object, which is stored in the transient--prefix property
of the same symbol.
level The level of the prefix commands. The suffix commands whose
layer is equal or lower are displayed. see Enabling and Disabling Suffixes.
value The likely outdated value of the prefix. Instead of accessing
this slot directly you should use the function transient-get-value,
which is guaranteed to return the up-to-date value.
history and history-pos are used to keep track of historic values.
Unless you implement your own transient-infix-read method you should
not have to deal with these slots.
Here we document most of the slots that are only available for suffix objects. Some slots are shared by suffix and group objects, they are documented in Predicate Slots.
Also see Suffix Classes.
transient-suffix ¶key The key, a key vector or a key description string.
command The command, a symbol.
transient Whether to stay transient. See Transient State.
format The format used to display the suffix in the popup buffer.
It must contain the following %-placeholders:
%k For the key.
%d For the description.
%v For the infix value. Non-infix suffixes don’t have a value.
description The description, either a string or a function that is
called with no argument and returns a string.
show-help A function used to display help for the suffix. If
unspecified, the prefix controls how help is displayed for its
suffixes.
transient-infix ¶Some of these slots are only meaningful for some of the subclasses. They are defined here anyway to allow sharing certain methods.
argument The long argument, e.g., --verbose.
shortarg The short argument, e.g., -v.
value The value. Should not be accessed directly.
init-value Function that is responsible for setting the object’s
value. If bound, then this is called with the object as the only
argument. Usually this is not bound, in which case the object’s
primary transient-init-value method is called instead.
unsavable Whether the value of the suffix is not saved as part of
the prefixes.
multi-value For options, whether the option can have multiple
values. If this is non-nil, then the values are read using
completing-read-multiple by default and if you specify your own
reader, then it should read the values using that function or
similar.
Supported non-nil values are:
rest for an option that can have multiple values. This is
useful e.g., for an -- argument that indicates that all remaining
arguments are files (such as git log -- file1 file2).
In the list returned by transient-args such an option and its
values are represented by a single list of the form (ARGUMENT
. VALUES).
repeat for an option that can be specified multiple times.
In the list returned by transient-args each instance of the option
and its value appears separately in the usual from, for example:
("--another-argument" "--option=first" "--option=second").
In both cases the option’s values have to be specified in the
default value of a prefix using the same format as returned by
transient-args, e.g., ("--other" "--o=1" "--o=2" ("--" "f1" "f2")).
always-read For options, whether to read a value on every invocation.
If this is nil, then options that have a value are simply unset and
have to be invoked a second time to set a new value.
allow-empty For options, whether the empty string is a valid value.
history-key The key used to store the history. This defaults to the
command name. This is useful when multiple infixes should share the
same history because their values are of the same kind.
reader The function used to read the value of an infix. Not used
for switches. The function takes three arguments, PROMPT,
INITIAL-INPUT and HISTORY, and must return a string.
prompt The prompt used when reading the value, either a string or a
function that takes the object as the only argument and which
returns a prompt string.
choices A list of valid values. How exactly that is used depends on
the class of the object.
transient-variable ¶variable The variable.
transient-switches ¶argument-format The display format. Must contain %s, one of the
choices is substituted for that. E.g., --%s-order.
argument-regexp The regexp used to match any one of the switches.
E.g., \\(--\\(topo\\|author-date\\|date\\)-order\\).
Suffix and group objects share some predicate slots that control whether a group or suffix should be available depending on some state. Only one of these slots can be used at the same time. It is undefined what happens if you use more than one.
if Enable if predicate returns non-nil.
if-not Enable if predicate returns nil.
if-non-nil Enable if variable’s value is non-nil.
if-nil Enable if variable’s value is nil.
if-mode Enable if major-mode matches value.
if-not-mode Enable if major-mode does not match value.
if-derived Enable if major-mode derives from value.
if-not-derived Enable if major-mode does not derive from value.
One more slot is shared between group and suffix classes, level. Like
the slots documented above, it is a predicate, but it is used for a
different purpose. The value has to be an integer between 1
and 7. level controls whether a suffix or a group should be
available depending on user preference.
See Enabling and Disabling Suffixes.
While transient commands were inspired by regular prefix keys and prefix arguments, they are also quite different and much more complex.
The following diagrams illustrate some of the differences.
See (elisp)Prefix Keys.
,--> command1 --> (c)
|
(c)-(+)-> prefix command or key --+--> command2 --> (c)
|
`--> command3 --> (c)
See (elisp)Prefix Command Arguments.
,----------------------------------,
| |
v |
(c)-(+)---> prefix argument command --(c)-(+)-> any command --> (c)
| ^ |
| | |
`-- sets or changes --, ,-- maybe used --' |
| | |
v | |
prefix argument state |
^ |
| |
`-------- discards --------'
(∩｀-´)⊃━☆ﾟ.*･｡ﾟ
This diagram ignores the infix value and external state:
(c)
| ,- {stay} ------<-,-<------------<-,-<---,
(+) | | | |
| | | | |
| | ,--> infix1 --| | |
| | | | | |
| | |--> infix2 --| | |
v v | | | |
prefix -(c)-(+)-> infix3 --' ^ |
| | |
|---------------> suffix1 -->--| |
| | |
|---------------> suffix2 ----{1}------> {exit} --> (c)
| |
|---------------> suffix3 -------------> {exit} --> (c)
| |
`--> any command --{2}-> {warn} -->--|
| |
|--> {noop} -->--|
| |
|--> {call} -->--'
|
`------------------> {exit} --> (c)
This diagram takes the infix value into account to an extend, while still ignoring external state:
(c)
| ,- {stay} ------<-,-<------------<-,-<---,
(+) | | | |
| | | | |
| | ,--> infix1 --| | |
| | | | | | |
| | ,--> infix2 --| | |
v v | | | | |
prefix -(c)-(+)-> infix3 --' | |
| | ^ |
| | | |
|---------------> suffix1 -->--| |
| | ^ | |
| | | | |
|---------------> suffix2 ----{1}------> {exit} --> (c)
| | ^ | |
| | | | v
| | | | |
|---------------> suffix3 -------------> {exit} --> (c)
| | ^ | |
| sets | | v
| | maybe | |
| | used | |
| | | | |
| | infix --' | |
| `---> value | |
| ^ | |
| | | |
| hides | |
| | | |
| `--------------------------<---|
| | |
`--> any command --{2}-> {warn} -->--| |
| | |
|--> {noop} -->--| |
| | |
|--> {call} -->--' ^
| |
`------------------> {exit} --> (c)
This diagram provides more information about the infix value and also takes external state into account.
,----sets--- "anything"
|
v
,---------> external
| state
| | |
| initialized | ☉‿⚆
sets from |
| | maybe
| ,----------' used
| | |
(c) | | v
| ,- {stay} --|---<-,-<------|-----<-,-<---,
(+) | | | | | | |
| | | v | | | |
| | ,--> infix1 --| | | |
| | | | | | | | |
| | | | v | | | |
| | ,--> infix2 --| | | |
| | | | ^ | | | |
v v | | | | | | |
prefix -(c)-(+)-> infix3 --' | | |
| | ^ | ^ |
| | | v | |
|---------------> suffix1 -->--| |
| | | ^ | | |
| | | | v | |
|---------------> suffix2 ----{1}------> {exit} --> (c)
| | | ^ | | |
| | | | | | v
| | | | v | |
|---------------> suffix3 -------------> {exit} --> (c)
| | | ^ | |
| sets | | | v
| | initialized maybe | |
| | from used | |
| | | | | |
| | `-- infix ---' | |
| `---> value -----------------------------> persistent
| ^ ^ | | across
| | | | | invocations -,
| hides | | | |
| | `----------------------------------------------'
| | | |
| `--------------------------<---|
| | |
`--> any command --{2}-> {warn} -->--| |
| | |
|--> {noop} -->--| |
| | |
|--> {call} -->--' ^
| |
`------------------> {exit} --> (c)
Despite already being rather complex, even the last diagram leaves out
many details. Most importantly it implies that the decision whether
to remain transient is made later than it actually is made (for the
most part a function on pre-command-hook is responsible). But such
implementation details are of little relevance to users and are
covered elsewhere.
Transient is the successor to Magit-Popup (see (magit-popup)Top).
One major difference between these two implementations of the same
ideas is that while Transient uses transient keymaps and embraces the
command-loop, Magit-Popup implemented an inferior mechanism that does
not use transient keymaps and that instead of using the command-loop
implements a naive alternative based on read-char.
Magit-Popup does not use classes and generic functions and defining a new command type is near impossible as it involves adding hard-coded special-cases to many functions. Because of that only a single new type was added, which was not already part of Magit-Popup’s initial release.
A lot of things are hard-coded in Magit-Popup. One random example is
that the key bindings for switches must begin with - and those for
options must begin with =.
Hydra (see https://github.com/abo-abo/hydra) is another package that provides features similar to those of Transient.
Both packages use transient keymaps to make a set of commands temporarily available and show the available commands in a popup buffer.
A Hydra “body” is equivalent to a Transient “prefix” and a Hydra “head” is equivalent to a Transient “suffix”. Hydra has no equivalent of a Transient “infix”.
Both hydras and transients can be used as simple command dispatchers. Used like this they are similar to regular prefix commands and prefix keys, except that the available commands are shown in the popup buffer.
(Another package that does this is which-key. It does so automatically
for any incomplete key sequence. The advantage of that approach is
that no additional work is necessary; the disadvantage is that the
available commands are not organized semantically.)
Both Hydra and Transient provide features that go beyond simple command dispatchers:
Transient supports that too, but for now this feature is not a focus and the interface is a bit more complicated. A very basic example using the current interface:
(transient-define-prefix outline-navigate ()
:transient-suffix 'transient--do-stay
:transient-non-suffix 'transient--do-warn
[("p" "previous visible heading" outline-previous-visible-heading)
("n" "next visible heading" outline-next-visible-heading)])
To my knowledge, Hydra does not support that.
Both packages make it possible to specify how exactly the available commands are outlined:
The downside of this is that it becomes harder for a user to add additional commands to an existing hydra and to change key bindings.
However while Transient supports giving sections a heading it does not currently support giving the displayed information more structure by, for example, using box-drawing characters.
That could be implemented by defining a new group class, which lets the author specify a format string. It should be possible to implement that without modifying any existing code, but it does not currently exist.
Yes, see transient-display-buffer-action in Configuration.
To be able to mark text in any transient popup buffer using the mouse, you have to add the following binding. Note that the region won’t be visualized, while doing so. After you have quit the transient popup, you will be able to yank it another buffer.
(keymap-set transient-predicate-map
"<mouse-set-region>"
#'transient--do-stay)
You may have noticed that the bindings for some of the common commands do not have the prefix C-x and that furthermore some of these commands are grayed out while others are not. That unfortunately is a bit confusing if the section of common commands is not shown permanently, making the following explanation necessary.
The purpose of usually hiding that section but showing it after the user pressed the respective prefix key is to conserve space and not overwhelm users with too much noise, while allowing the user to quickly list common bindings on demand.
That however should not keep us from using the best possible key bindings. The bindings that do use a prefix do so to avoid wasting too many non-prefix bindings, keeping them available for use in individual transients. The bindings that do not use a prefix and that are not grayed out are very important bindings that are always available, even when invoking the “common command key prefix” or any other transient-specific prefix. The non-prefix keys that are grayed out however, are not available when any incomplete prefix key sequence is active. They do not use the “common command key prefix” because it is likely that users want to invoke them several times in a row and e.g., M-p M-p M-p is much more convenient than C-x M-p C-x M-p C-x M-p.
You may also have noticed that the “Set” command is bound to C-x s, while Magit-Popup used to bind C-c C-c instead. I have seen several users praise the latter binding (sic), so I did not change it willy-nilly. The reason that I changed it is that using different prefix keys for different common commands, would have made the temporary display of the common commands even more confusing, i.e., after pressing C-c all the bindings that begin with the C-x prefix would be grayed out.
Using a single prefix for common commands key means that all other potential prefix keys can be used for transient-specific commands without the section of common commands also popping up. C-c in particular is a prefix that I want to (and already do) use for Magit, and also using that for a common command would prevent me from doing so.
(Also see the next question.)
I agree that q is a good binding for commands that quit something.
This includes quitting whatever transient is currently active, but it
also includes quitting whatever it is that some specific transient is
controlling. The transient magit-blame for example binds q to the
command that turns magit-blame-mode off.
So I had to decide if q should quit the active transient (like Magit-Popup used to) or whether C-g should do that instead, so that q could be bound in individual transient to whatever commands make sense for them. Because all other letters are already reserved for use by individual transients, I have decided to no longer make an exception for q.
If you want to get q’s old binding back then you can do so. Doing
that is a bit more complicated than changing a single key binding, so
I have implemented a function, transient-bind-q-to-quit that makes the
necessary changes. See its doc string for more information.
Copyright © 2007 Free Software Foundation, Inc. https://fsf.org/ Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
The GNU General Public License is a free, copyleft license for software and other kinds of works.
The licenses for most software and other practical works are designed to take away your freedom to share and change the works. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change all versions of a program—to make sure it remains free software for all its users. We, the Free Software Foundation, use the GNU General Public License for most of our software; it applies also to any other work released this way by its authors. You can apply it to your programs, too.
When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for them if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs, and that you know you can do these things.
To protect your rights, we need to prevent others from denying you these rights or asking you to surrender the rights. Therefore, you have certain responsibilities if you distribute copies of the software, or if you modify it: responsibilities to respect the freedom of others.
For example, if you distribute copies of such a program, whether gratis or for a fee, you must pass on to the recipients the same freedoms that you received. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.
Developers that use the GNU GPL protect your rights with two steps: (1) assert copyright on the software, and (2) offer you this License giving you legal permission to copy, distribute and/or modify it.
For the developers’ and authors’ protection, the GPL clearly explains that there is no warranty for this free software. For both users’ and authors’ sake, the GPL requires that modified versions be marked as changed, so that their problems will not be attributed erroneously to authors of previous versions.
Some devices are designed to deny users access to install or run modified versions of the software inside them, although the manufacturer can do so. This is fundamentally incompatible with the aim of protecting users’ freedom to change the software. The systematic pattern of such abuse occurs in the area of products for individuals to use, which is precisely where it is most unacceptable. Therefore, we have designed this version of the GPL to prohibit the practice for those products. If such problems arise substantially in other domains, we stand ready to extend this provision to those domains in future versions of the GPL, as needed to protect the freedom of users.
Finally, every program is threatened constantly by software patents. States should not allow patents to restrict development and use of software on general-purpose computers, but in those that do, we wish to avoid the special danger that patents applied to a free program could make it effectively proprietary. To prevent this, the GPL assures that patents cannot be used to render the program non-free.
The precise terms and conditions for copying, distribution and modification follow.
“This License” refers to version 3 of the GNU General Public License.
“Copyright” also means copyright-like laws that apply to other kinds of works, such as semiconductor masks.
“The Program” refers to any copyrightable work licensed under this License. Each licensee is addressed as “you”. “Licensees” and “recipients” may be individuals or organizations.
To “modify” a work means to copy from or adapt all or part of the work in a fashion requiring copyright permission, other than the making of an exact copy. The resulting work is called a “modified version” of the earlier work or a work “based on” the earlier work.
A “covered work” means either the unmodified Program or a work based on the Program.
To “propagate” a work means to do anything with it that, without permission, would make you directly or secondarily liable for infringement under applicable copyright law, except executing it on a computer or modifying a private copy. Propagation includes copying, distribution (with or without modification), making available to the public, and in some countries other activities as well.
To “convey” a work means any kind of propagation that enables other parties to make or receive copies. Mere interaction with a user through a computer network, with no transfer of a copy, is not conveying.
An interactive user interface displays “Appropriate Legal Notices” to the extent that it includes a convenient and prominently visible feature that (1) displays an appropriate copyright notice, and (2) tells the user that there is no warranty for the work (except to the extent that warranties are provided), that licensees may convey the work under this License, and how to view a copy of this License. If the interface presents a list of user commands or options, such as a menu, a prominent item in the list meets this criterion.
The “source code” for a work means the preferred form of the work for making modifications to it. “Object code” means any non-source form of a work.
A “Standard Interface” means an interface that either is an official standard defined by a recognized standards body, or, in the case of interfaces specified for a particular programming language, one that is widely used among developers working in that language.
The “System Libraries” of an executable work include anything, other than the work as a whole, that (a) is included in the normal form of packaging a Major Component, but which is not part of that Major Component, and (b) serves only to enable use of the work with that Major Component, or to implement a Standard Interface for which an implementation is available to the public in source code form. A “Major Component”, in this context, means a major essential component (kernel, window system, and so on) of the specific operating system (if any) on which the executable work runs, or a compiler used to produce the work, or an object code interpreter used to run it.
The “Corresponding Source” for a work in object code form means all the source code needed to generate, install, and (for an executable work) run the object code and to modify the work, including scripts to control those activities. However, it does not include the work’s System Libraries, or general-purpose tools or generally available free programs which are used unmodified in performing those activities but which are not part of the work. For example, Corresponding Source includes interface definition files associated with source files for the work, and the source code for shared libraries and dynamically linked subprograms that the work is specifically designed to require, such as by intimate data communication or control flow between those subprograms and other parts of the work.
The Corresponding Source need not include anything that users can regenerate automatically from other parts of the Corresponding Source.
The Corresponding Source for a work in source code form is that same work.
All rights granted under this License are granted for the term of copyright on the Program, and are irrevocable provided the stated conditions are met. This License explicitly affirms your unlimited permission to run the unmodified Program. The output from running a covered work is covered by this License only if the output, given its content, constitutes a covered work. This License acknowledges your rights of fair use or other equivalent, as provided by copyright law.
You may make, run and propagate covered works that you do not convey, without conditions so long as your license otherwise remains in force. You may convey covered works to others for the sole purpose of having them make modifications exclusively for you, or provide you with facilities for running those works, provided that you comply with the terms of this License in conveying all material for which you do not control copyright. Those thus making or running the covered works for you must do so exclusively on your behalf, under your direction and control, on terms that prohibit them from making any copies of your copyrighted material outside their relationship with you.
Conveying under any other circumstances is permitted solely under the conditions stated below. Sublicensing is not allowed; section 10 makes it unnecessary.
No covered work shall be deemed part of an effective technological measure under any applicable law fulfilling obligations under article 11 of the WIPO copyright treaty adopted on 20 December 1996, or similar laws prohibiting or restricting circumvention of such measures.
When you convey a covered work, you waive any legal power to forbid circumvention of technological measures to the extent such circumvention is effected by exercising rights under this License with respect to the covered work, and you disclaim any intention to limit operation or modification of the work as a means of enforcing, against the work’s users, your or third parties’ legal rights to forbid circumvention of technological measures.
You may convey verbatim copies of the Program’s source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice; keep intact all notices stating that this License and any non-permissive terms added in accord with section 7 apply to the code; keep intact all notices of the absence of any warranty; and give all recipients a copy of this License along with the Program.
You may charge any price or no price for each copy that you convey, and you may offer support or warranty protection for a fee.
You may convey a work based on the Program, or the modifications to produce it from the Program, in the form of source code under the terms of section 4, provided that you also meet all of these conditions:
A compilation of a covered work with other separate and independent works, which are not by their nature extensions of the covered work, and which are not combined with it such as to form a larger program, in or on a volume of a storage or distribution medium, is called an “aggregate” if the compilation and its resulting copyright are not used to limit the access or legal rights of the compilation’s users beyond what the individual works permit. Inclusion of a covered work in an aggregate does not cause this License to apply to the other parts of the aggregate.
You may convey a covered work in object code form under the terms of sections 4 and 5, provided that you also convey the machine-readable Corresponding Source under the terms of this License, in one of these ways:
A separable portion of the object code, whose source code is excluded from the Corresponding Source as a System Library, need not be included in conveying the object code work.
A “User Product” is either (1) a “consumer product”, which means any tangible personal property which is normally used for personal, family, or household purposes, or (2) anything designed or sold for incorporation into a dwelling. In determining whether a product is a consumer product, doubtful cases shall be resolved in favor of coverage. For a particular product received by a particular user, “normally used” refers to a typical or common use of that class of product, regardless of the status of the particular user or of the way in which the particular user actually uses, or expects or is expected to use, the product. A product is a consumer product regardless of whether the product has substantial commercial, industrial or non-consumer uses, unless such uses represent the only significant mode of use of the product.
“Installation Information” for a User Product means any methods, procedures, authorization keys, or other information required to install and execute modified versions of a covered work in that User Product from a modified version of its Corresponding Source. The information must suffice to ensure that the continued functioning of the modified object code is in no case prevented or interfered with solely because modification has been made.
If you convey an object code work under this section in, or with, or specifically for use in, a User Product, and the conveying occurs as part of a transaction in which the right of possession and use of the User Product is transferred to the recipient in perpetuity or for a fixed term (regardless of how the transaction is characterized), the Corresponding Source conveyed under this section must be accompanied by the Installation Information. But this requirement does not apply if neither you nor any third party retains the ability to install modified object code on the User Product (for example, the work has been installed in ROM).
The requirement to provide Installation Information does not include a requirement to continue to provide support service, warranty, or updates for a work that has been modified or installed by the recipient, or for the User Product in which it has been modified or installed. Access to a network may be denied when the modification itself materially and adversely affects the operation of the network or violates the rules and protocols for communication across the network.
Corresponding Source conveyed, and Installation Information provided, in accord with this section must be in a format that is publicly documented (and with an implementation available to the public in source code form), and must require no special password or key for unpacking, reading or copying.
“Additional permissions” are terms that supplement the terms of this License by making exceptions from one or more of its conditions. Additional permissions that are applicable to the entire Program shall be treated as though they were included in this License, to the extent that they are valid under applicable law. If additional permissions apply only to part of the Program, that part may be used separately under those permissions, but the entire Program remains governed by this License without regard to the additional permissions.
When you convey a copy of a covered work, you may at your option remove any additional permissions from that copy, or from any part of it. (Additional permissions may be written to require their own removal in certain cases when you modify the work.) You may place additional permissions on material, added by you to a covered work, for which you have or can give appropriate copyright permission.
Notwithstanding any other provision of this License, for material you add to a covered work, you may (if authorized by the copyright holders of that material) supplement the terms of this License with terms:
All other non-permissive additional terms are considered “further restrictions” within the meaning of section 10. If the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term. If a license document contains a further restriction but permits relicensing or conveying under this License, you may add to a covered work material governed by the terms of that license document, provided that the further restriction does not survive such relicensing or conveying.
If you add terms to a covered work in accord with this section, you must place, in the relevant source files, a statement of the additional terms that apply to those files, or a notice indicating where to find the applicable terms.
Additional terms, permissive or non-permissive, may be stated in the form of a separately written license, or stated as exceptions; the above requirements apply either way.
You may not propagate or modify a covered work except as expressly provided under this License. Any attempt otherwise to propagate or modify it is void, and will automatically terminate your rights under this License (including any patent licenses granted under the third paragraph of section 11).
However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.
Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.
Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, you do not qualify to receive new licenses for the same material under section 10.
You are not required to accept this License in order to receive or run a copy of the Program. Ancillary propagation of a covered work occurring solely as a consequence of using peer-to-peer transmission to receive a copy likewise does not require acceptance. However, nothing other than this License grants you permission to propagate or modify any covered work. These actions infringe copyright if you do not accept this License. Therefore, by modifying or propagating a covered work, you indicate your acceptance of this License to do so.
Each time you convey a covered work, the recipient automatically receives a license from the original licensors, to run, modify and propagate that work, subject to this License. You are not responsible for enforcing compliance by third parties with this License.
An “entity transaction” is a transaction transferring control of an organization, or substantially all assets of one, or subdividing an organization, or merging organizations. If propagation of a covered work results from an entity transaction, each party to that transaction who receives a copy of the work also receives whatever licenses to the work the party’s predecessor in interest had or could give under the previous paragraph, plus a right to possession of the Corresponding Source of the work from the predecessor in interest, if the predecessor has it or can get it with reasonable efforts.
You may not impose any further restrictions on the exercise of the rights granted or affirmed under this License. For example, you may not impose a license fee, royalty, or other charge for exercise of rights granted under this License, and you may not initiate litigation (including a cross-claim or counterclaim in a lawsuit) alleging that any patent claim is infringed by making, using, selling, offering for sale, or importing the Program or any portion of it.
A “contributor” is a copyright holder who authorizes use under this License of the Program or a work on which the Program is based. The work thus licensed is called the contributor’s “contributor version”.
A contributor’s “essential patent claims” are all patent claims owned or controlled by the contributor, whether already acquired or hereafter acquired, that would be infringed by some manner, permitted by this License, of making, using, or selling its contributor version, but do not include claims that would be infringed only as a consequence of further modification of the contributor version. For purposes of this definition, “control” includes the right to grant patent sublicenses in a manner consistent with the requirements of this License.
Each contributor grants you a non-exclusive, worldwide, royalty-free patent license under the contributor’s essential patent claims, to make, use, sell, offer for sale, import and otherwise run, modify and propagate the contents of its contributor version.
In the following three paragraphs, a “patent license” is any express agreement or commitment, however denominated, not to enforce a patent (such as an express permission to practice a patent or covenant not to sue for patent infringement). To “grant” such a patent license to a party means to make such an agreement or commitment not to enforce a patent against the party.
If you convey a covered work, knowingly relying on a patent license, and the Corresponding Source of the work is not available for anyone to copy, free of charge and under the terms of this License, through a publicly available network server or other readily accessible means, then you must either (1) cause the Corresponding Source to be so available, or (2) arrange to deprive yourself of the benefit of the patent license for this particular work, or (3) arrange, in a manner consistent with the requirements of this License, to extend the patent license to downstream recipients. “Knowingly relying” means you have actual knowledge that, but for the patent license, your conveying the covered work in a country, or your recipient’s use of the covered work in a country, would infringe one or more identifiable patents in that country that you have reason to believe are valid.
If, pursuant to or in connection with a single transaction or arrangement, you convey, or propagate by procuring conveyance of, a covered work, and grant a patent license to some of the parties receiving the covered work authorizing them to use, propagate, modify or convey a specific copy of the covered work, then the patent license you grant is automatically extended to all recipients of the covered work and works based on it.
A patent license is “discriminatory” if it does not include within the scope of its coverage, prohibits the exercise of, or is conditioned on the non-exercise of one or more of the rights that are specifically granted under this License. You may not convey a covered work if you are a party to an arrangement with a third party that is in the business of distributing software, under which you make payment to the third party based on the extent of your activity of conveying the work, and under which the third party grants, to any of the parties who would receive the covered work from you, a discriminatory patent license (a) in connection with copies of the covered work conveyed by you (or copies made from those copies), or (b) primarily for and in connection with specific products or compilations that contain the covered work, unless you entered into that arrangement, or that patent license was granted, prior to 28 March 2007.
Nothing in this License shall be construed as excluding or limiting any implied license or other defenses to infringement that may otherwise be available to you under applicable patent law.
If conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot convey a covered work so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not convey it at all. For example, if you agree to terms that obligate you to collect a royalty for further conveying from those to whom you convey the Program, the only way you could satisfy both those terms and this License would be to refrain entirely from conveying the Program.
Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU Affero General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such.
The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.
Each version is given a distinguishing version number. If the Program specifies that a certain numbered version of the GNU General Public License “or any later version” applies to it, you have the option of following the terms and conditions either of that numbered version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of the GNU General Public License, you may choose any version ever published by the Free Software Foundation.
If the Program specifies that a proxy can decide which future versions of the GNU General Public License can be used, that proxy’s public statement of acceptance of a version permanently authorizes you to choose that version for the Program.
Later license versions may give you additional or different permissions. However, no additional obligations are imposed on any author or copyright holder as a result of your choosing to follow a later version.
THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the Program in return for a fee.
If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
one line to give the program's name and a brief idea of what it does. Copyright (C) year name of author This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.
Also add information on how to contact you by electronic and paper mail.
If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode:
program Copyright (C) year name of author This program comes with ABSOLUTELY NO WARRANTY; for details type ‘show w’. This is free software, and you are welcome to redistribute it under certain conditions; type ‘show c’ for details.
The hypothetical commands ‘show w’ and ‘show c’ should show the appropriate parts of the General Public License. Of course, your program’s commands might be different; for a GUI interface, you would use an “about box”.
You should also get your employer (if you work as a programmer) or school, if any, to sign a “copyright disclaimer” for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see https://www.gnu.org/licenses/.
The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read https://www.gnu.org/licenses/why-not-lgpl.html.
magit-diff and magit-log are two prominent examples, and their
handling of buffer-local values is actually a bit more complicated
than outlined above and even customizable.