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https://github.com/minad/marginalia

:scroll: marginalia.el - Marginalia in the minibuffer
https://github.com/minad/marginalia

annotations emacs minibuffer

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:scroll: marginalia.el - Marginalia in the minibuffer

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README 

        
#+title: marginalia.el - Marginalia in the minibuffer

#+author: Omar Antolín Camarena, Daniel Mendler

#+language: en

#+export_file_name: marginalia.texi

#+texinfo_dir_category: Emacs misc features

#+texinfo_dir_title: Marginalia: (marginalia).

#+texinfo_dir_desc: Marginalia in the minibuffer



#+html: GNU Emacs

#+html: GNU ELPA

#+html: GNU-devel ELPA

#+html: MELPA

#+html: MELPA Stable



#+html: 



This package provides =marginalia-mode= which adds marginalia to the minibuffer

completions. [[https://en.wikipedia.org/wiki/Marginalia][Marginalia]] are marks or annotations placed at the margin of the

page of a book or in this case helpful colorful annotations placed at the margin

of the minibuffer for your completion candidates. Marginalia can only add

annotations to the completion candidates. It cannot modify the appearance of the

candidates themselves, which are shown unaltered as supplied by the original

command.



The annotations are added based on the completion category. For example

=find-file= reports the =file= category and =M-x= reports the =command= category. You

can cycle between more or less detailed annotators or even disable the annotator

with command =marginalia-cycle=.



#+html: 



#+toc: headlines 8



* Configuration



It is recommended to use Marginalia together with either the [[https://github.com/minad/vertico][Vertico]], [[https://github.com/protesilaos/mct][Mct]],

[[https://www.gnu.org/software/emacs/manual/html_node/emacs/Icomplete.html][Icomplete]] or the default completion UI. Furthermore Marginalia can be combined

with [[https://github.com/oantolin/embark][Embark]] for action support and [[https://github.com/minad/consult][Consult]], which provides many useful commands.



#+begin_src emacs-lisp

;; Enable rich annotations using the Marginalia package

(use-package marginalia

  ;; Bind `marginalia-cycle' locally in the minibuffer.  To make the binding

  ;; available in the *Completions* buffer, add it to the

  ;; `completion-list-mode-map'.

  :bind (:map minibuffer-local-map

         ("M-A" . marginalia-cycle))



  ;; The :init section is always executed.

  :init



  ;; Marginalia must be activated in the :init section of use-package such that

  ;; the mode gets enabled right away. Note that this forces loading the

  ;; package.

  (marginalia-mode))

#+end_src



* Information shown by the annotators



In general, to learn more about what different annotations mean, a good starting

point is to look at ~marginalia-annotator-registry~, and follow up to the

annotation function of the category you are interested in.



For example the annotations for Elisp symbols include their symbol class - =v= for

variable, =f= for function, =c= for command, etc. For more information on what the

different classifications mean, see the docstring of ~marginalia--symbol-class~.



* Adding custom annotators or classifiers



*IMPORTANT NOTICE FOR PACKAGE AUTHORS*: The intention of the Marginalia package is

to give the user means to overwrite completion categories and to add custom

annotators for existing commands in their user configuration. *Marginalia is a

user facing package and is not intended to be used as a library*. Therefore

Marginalia does not expose library functions as part of its public API. If you

add your own completion commands to your package we recommend to specify an

=annotation-function= or an =affixation-function=, avoiding the Marginalia

dependency this way. The =annotation-function= and =affixation-function= are

documented in the [[https://www.gnu.org/software/emacs/manual/html_node/elisp/Completion.html][Elisp manual]]. If you use =consult--read=, you can specify an

=:annotate= keyword argument.



There is an exception to our recommendation: If you want to implement

annotations for an existing package =hypothetic.el=, which does not have

annotations and where annotations cannot be added, then the creation of a

=marginalia-hypothetic.el= package is a good idea, since Marginalia provides the

facilities to enhance existing commands from the outside.



Commands that support minibuffer completion use a completion table of all the

available candidates. Candidates are associated with a *category* such as =command=,

=file=, =face=, or =variable= depending on what the candidates are. Based on the

category of the candidates, Marginalia selects an *annotator* to generate

annotations for display for each candidate.



Unfortunately, not all commands (including Emacs' builtin ones) specify the

category of their candidates. To compensate for this shortcoming, Marginalia

hooks into the Emacs completion framework and runs the *classifiers* listed in the

variable =marginalia-classifiers=, which use the command's prompt or other

properties of the candidates to specify the completion category.



For example, the =marginalia-classify-by-prompt= classifier checks the minibuffer

prompt against regexps listed in the =marginalia-prompt-categories= alist to

determine a category. The following is already included but would be a way to

assign the category =face= to all candidates from commands with prompts that

include the word "face".



#+begin_src emacs-lisp

  (add-to-list 'marginalia-prompt-categories '("\\" . face))

#+end_src



The =marginalia-classify-by-command-name= classifier uses the alist

=marginalia-command-categories= to specify the completion category based on the

command name. This is particularly useful if the prompt classifier yields a

false positive.



Completion categories are also important for [[https://github.com/oantolin/embark][Embark]], which associates actions

based on the completion category and benefits from Marginalia's classifiers.



Once the category of the candidates is known, Marginalia looks in the

=marginalia-annotator-registry= to find the associated annotator to use. An

annotator is a function that takes a completion candidate string as an argument

and returns an annotation string to be displayed after the candidate in the

minibuffer. More than one annotator can be assigned to each each category,

displaying more, less or different information. Use the =marginalia-cycle= command

to cycle between the annotations of different annotators defined for the current

category.



Here's an example of a basic face annotator:



#+begin_src emacs-lisp

  (defun my-face-annotator (cand)

    (when-let (sym (intern-soft cand))

      (concat (propertize " " 'display '(space :align-to center))

              (propertize "The quick brown fox jumps over the lazy dog" 'face sym))))

#+end_src



After defining a new annotator, associate it with a category in the annotator

registry as follows:



#+begin_src emacs-lisp

  (add-to-list 'marginalia-annotator-registry

               '(face my-face-annotator marginalia-annotate-face builtin none))

#+end_src



This makes the =my-face-annotator= the first of four annotators for the face

category. The others are the annotator provided by Marginalia

(=marginalia-annotate-face=), the =builtin= annotator as defined by Emacs and the

=none= annotator, which disables the annotations. With this setting, after

invoking =M-x describe-face RET= you can cycle between all of these annotators

using =marginalia-cycle=.



* Disabling annotators, builtin or lightweight annotators



Marginalia activates rich annotators by default. Depending on your preference

you may want to use the builtin annotators or even no annotators by default and

only activate the annotators on demand by invoking ~marginalia-cycle~.



In order to disable an annotator permanently, the ~marginalia-annotator-registry~

can be modified. For example if you prefer to never see file annotations, you

can delete all file annotators from the registry.



#+begin_src emacs-lisp

  (setq marginalia-annotator-registry

        (assq-delete-all 'file marginalia-annotator-registry))

#+end_src



To use the builtin annotators by default, you can run the following code.

Replace =builtin= by =none= to disable annotators by default.



#+begin_src emacs-lisp

(mapc (lambda (x)

        (setcdr x (cons 'builtin (remq 'builtin (cdr x)))))

      marginalia-annotator-registry)

#+end_src



As an alternative to ~marginalia-cycle~, if a completion category supports two

annotators, you can toggle between them using the following command.



#+begin_src emacs-lisp

  (defun marginalia-toggle ()

    (interactive)

    (mapc

     (lambda (x)

       (setcdr x (append (reverse (remq 'none

                                        (remq 'builtin (cdr x))))

                         '(builtin none))))

     marginalia-annotator-registry))

#+end_src



After cycling the annotators you may want to automatically save the

configuration. This can be achieved using an advice which calls

~customize-save-variable~.



#+begin_src emacs-lisp

  (advice-add #'marginalia-cycle :after

              (lambda ()

                (let ((inhibit-message t))

                  (customize-save-variable 'marginalia-annotator-registry

                                           marginalia-annotator-registry))))

#+end_src



* Icons in the minibuffer



Marginalia focuses on text annotations. The [[https://github.com/rainstormstudio/nerd-icons-completion][nerd-icons-completion]] package is

compatible with Marginalia and uses the special NerdFonts to add icons in front

of minibuffer completion candidates. There exist related packages to enhance

Dired, Ibuffer, Corfu and other modes with icons consistently.



* Contributions



Since this package is part of [[https://elpa.gnu.org/packages/marginalia.html][GNU ELPA]] contributions require a copyright

assignment to the FSF.