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5.4 Suffix Classes ¶

• All suffix and infix classes derive from transient-suffix, which in turn derives from transient-child, from which transient-group also derives (see Group Classes).
• All infix classes derive from the abstract 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).

• Classes used for infix commands that represent arguments should be derived from the abstract transient-argument class.
• The transient-switch class (or a derived class) is used for infix arguments that represent command-line switches (arguments that do not take a value).
• The transient-option class (or a derived class) is used for infix arguments that represent command-line options (arguments that do take a value).
• The transient-switches class can be used for a set of mutually exclusive command-line switches.
• The transient-files class can be used for a ‘--’ argument that indicates that all remaining arguments are files.
• Classes used for infix commands that represent variables should derived from the abstract transient-variable class.
• The transient-information and transient-information* classes are special in that suffixes that use these class are not associated with a command and thus also not with any key binding. Such suffixes are only used to display arbitrary information, and that anywhere a suffix can appear. Display-only suffix specifications take these form:

  (:info DESCRIPTION [KEYWORD VALUE]...)
  (:info* DESCRIPTION [KEYWORD VALUE]...)
  

  The :info and :info* keyword arguments replaces the :description keyword used for other suffix classes. Other keyword arguments that you might want to set, include :face, predicate keywords (such as :if and :inapt-if), and :format. By default the value of :format includes %k, which for this class is replaced with the empty string or spaces, if keys are being padded in the containing group.

  The only difference between these two classes is that :info* aligns its description with the descriptions of suffix commands, while for :info the description bleeds into the area where suffixes display their key bindings.

• The transient-lisp-variable class can be used to show and change the value of lisp variables. This class is not fully featured yet and it is somewhat likely that future improvements won’t be fully backward compatible.
• The transient-cons-option class is intended for situations where transient-args should return an alist, instead of a list of strings (arguments). Such suffixes can be specified in prefix definitions like so:

  (:cons OPTION :key KEY [KEYWORD VALUE]...)
  

  OPTION may be something other than a string, likely a keyword or some other symbol, it is used as the car of the cons-cell. When using such an inline definition :key has to be specified. In most cases :reader should also be specified. When defining such a suffix separately, the "alist key" has to be specified using the :variable keyword argument.

  This class is still experimental it is somewhat likely that future improvements won’t be fully backward compatible.

• The transient-describe-target class is used by the command transient-describe.
• The transient-value-preset class is used to implement the command transient-preset, which activates a value preset.

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.