1 #+SETUPFILE: org-setup.inc
3 #+TITLE: Expanding snippets
5 This section describes how YASnippet chooses snippets for expansion at point.
7 Maybe, you'll want some snippets to be expanded in a particular
8 mode, or only under certain conditions, or be prompted using
10 * Triggering expansion
12 You can use YASnippet to expand snippets in different ways:
14 - When [[sym:yas-minor-mode][=yas-minor-mode=]] is active:
15 - Type the snippet's *trigger key* then calling [[sym:yas-expand][=yas-expand=]]
16 (bound to =TAB= by default).
18 - Use the snippet's *keybinding*.
20 - By expanding directly from the "YASnippet" menu in the menu-bar
24 - Call [[sym:yas-insert-snippet][=yas-insert-snippet=]] (use =M-x yas-insert-snippet== or its
25 keybinding =C-c & C-s=).
27 - Use m2m's excellent auto-complete
28 TODO: example for this
30 - Expanding from emacs-lisp code
34 [[sym:yas-expand][=yas-expand=]] tries to expand a /snippet abbrev/ (also known as
35 /snippet key/) before point.
37 When [[sym:yas-minor-mode][=yas-minor-mode=]] is enabled, it binds [[sym:yas-expand][=yas-expand=]] to =TAB= and
38 =<tab>= by default, however, you can freely set it to some other key:
40 #+begin_src emacs-lisp :exports code
41 (define-key yas-minor-mode-map (kbd "<tab>") nil)
42 (define-key yas-minor-mode-map (kbd "TAB") nil)
43 (define-key yas-minor-mode-map (kbd "<the new key>") 'yas-expand)
46 To enable the YASnippet minor mode in all buffers globally use the
47 command [[sym:yas-global-mode][=yas-global-mode=]]. This will enable a modeline indicator,
50 [[./images/minor-mode-indicator.png]]
52 When you use [[sym:yas-global-mode][=yas-global-mode=]] you can also selectively disable
53 YASnippet in some buffers by setting the buffer-local variable
54 [[sym:yas-dont-active][=yas-dont-active=]] in the buffer's mode hook.
56 *** Fallback behaviour
58 [[sym:yas-fallback-behaviour][=yas-fallback-behaviour=]] is a customization variable bound to
59 '=call-other-command= by default. If [[sym:yas-expand][=yas-expand=]] failed to find any
60 suitable snippet to expand, it will disable the minor mode temporarily
61 and find if there's any other command bound to the same key.
63 If found, the command will be called. Usually this works very well
64 --when there's a snippet, expand it, otherwise, call whatever command
65 originally bind to the trigger key.
67 However, you can change this behavior by customizing the
68 [[sym:yas-fallback-behavior][=yas-fallback-behavior=]] variable. If you set this variable to
69 '=return-nil=, it will return =nil= instead of trying to call the
70 /original/ command when no snippet is found.
74 The command [[#yas-insert-snippet][=yas-insert-snippet=]] lets you insert snippets at point
75 /for your current major mode/. It prompts you for the snippet key
76 first, and then for a snippet template if more than one template
77 exists for the same key.
79 The list presented contains the snippets that can be inserted at point,
80 according to the condition system. If you want to see all applicable
81 snippets for the major mode, prefix this command with =C-u=.
83 The prompting methods used are again controlled by
84 [[sym:yas-prompt-functions][=yas-prompt-functions=]].
88 See the section of the =# binding:= directive in
89 [[./snippet-development.org][Writing Snippets]].
91 ** Expanding from the menu
93 See [[./snippet-menu.org][the YASnippet Menu]].
95 ** Expanding with =hippie-expand=
97 To integrate with =hippie-expand=, just put
98 [[sym:yas-hippie-try-expand][=yas-hippie-try-expand=]] in
99 =hippie-expand-try-functions-list=. This probably makes more sense
100 when placed at the top of the list, but it can be put anywhere you
103 ** Expanding from emacs-lisp code
105 Sometimes you might want to expand a snippet directly from your own
106 elisp code. You should call [[sym:yas-expand-snippet][=yas-expand-snippet=]] instead of
107 [[sym:yas-expand][=yas-expand=]] in this case. [[sym:yas-expand-snippet][=yas-expand-snippet=]] takes a string in
108 snippet template syntax, if you want to expand an existing snippet you
109 can use [[sym:yas-lookup-snippet][=yas-lookup-snippet=]] to find its contents by name.
111 As with expanding from the menubar, the condition system and multiple
112 candidates doesn't affect expansion (the condition system does affect
113 [[sym:yas-lookup-snippet][=yas-lookup-snippet=]] though). In fact, expanding from the YASnippet
114 menu has the same effect of evaluating the follow code:
116 #+BEGIN_SRC emacs-lisp
117 (yas-expand-snippet template)
120 See the internal documentation on [[sym:yas-expand-snippet][=yas-expand-snippet=]] and
121 [[sym:yas-lookup-snippet][=yas-lookup-snippet=]] for more information.
123 * Controlling expansion
127 YASnippet does quite a bit of filtering to find out which snippets are
128 eligible for expanding at the current cursor position.
130 In particular, the following things matter:
132 - Currently loaded snippets tables
134 These are loaded from a directory hierarchy in your file system. See
135 [[./snippet-organization.org][Organizing Snippets]]. They are named
136 after major modes like =html-mode=, =ruby-mode=, etc...
138 - Major mode of the current buffer
140 If the currrent major mode matches one of the loaded snippet tables,
141 then all that table's snippets are considered for expansion. Use
142 =M-x describe-variable RET major-mode RET= to find out which major
143 mode you are in currently.
147 Snippet tables defined as the parent of some other eligible table are
148 also considered. This works recursively, i.e. parents of parents of
149 eligible tables are also considered.
151 - Buffer-local list of extra modes
153 Use [[#yas-activate-extra-mode][=yas-activate-extra-mode=]] to
154 consider snippet tables whose name does not correspond to a major
155 mode. Typically, you call this from a minor mode hook, for example:
157 #+BEGIN_SRC emacs-lisp
158 ;; When entering rinari-minor-mode, consider also the snippets in the
159 ;; snippet table "rails-mode"
160 (add-hook 'rinari-minor-mode-hook
162 (yas-activate-extra-mode 'rails-mode)))
166 [[sym:yas-buffer-local-condition][=yas-buffer-local-condition=]]
169 This variable provides finer grained control over what snippets can
170 be expanded in the current buffer. The default value won't let you
171 expand snippets inside comments or string literals for example. See
172 The condition system\_ for more info.
174 ** The condition system
176 Consider this scenario: you are an old Emacs hacker. You like the
177 abbrev-way and bind [[sym:yas-expand][=yas-expand=]] to =SPC=. However, you don't want
178 =if= to be expanded as a snippet when you are typing in a comment
179 block or a string (e.g. in =python-mode=).
181 If you use the =# condition := directive (see
182 [[./snippet-development.org][Writing Snippets]]) you could just specify
183 the condition for =if= to be =(not (python-in-string/comment))=. But how
184 about =while=, =for=, etc. ? Writing the same condition for all the
185 snippets is just boring. So has a buffer local variable
186 [[sym:yas-buffer-local-condition][=yas-buffer-local-condition=]]. You can set this variable to
187 =(not (python-in-string/comment))= in =python-mode-hook=.
189 Then, what if you really want some particular snippet to expand even
190 inside a comment? Set [[sym:yas-buffer-local-condition][=yas-buffer-local-condition=]] like this
192 #+BEGIN_SRC emacs-lisp
193 (add-hook 'python-mode-hook
195 (setq yas-buffer-local-condition
196 '(if (python-in-string/comment)
197 '(require-snippet-condition . force-in-comment)
201 ... and specify the condition for a snippet that you're going to expand
202 in comment to be evaluated to the symbol =force-in-comment=. Then it can
203 be expanded as you expected, while other snippets like =if= still can't
206 For the full set of possible conditions, see the documentation for
207 [[sym:yas-buffer-local-condition][=yas-buffer-local-condition=]].
209 ** Multiples snippet with the same key
211 The rules outlined [[Eligible%20snippets][above]] can return more than
212 one snippet to be expanded at point.
214 When there are multiple candidates, YASnippet will let you select one.
215 The UI for selecting multiple candidate can be customized through
216 [[sym:yas-prompt-functions][=yas-prompt-functions=]] , which defines your preferred methods of being
217 prompted for snippets.
219 You can customize it with
220 =M-x customize-variable RET yas-prompt-functions RET=. Alternatively you
221 can put in your emacs-file:
223 #+BEGIN_SRC emacs-lisp
224 (setq yas-prompt-functions '(yas-x-prompt yas-dropdown-prompt))
227 Currently there are some alternatives solution with YASnippet.
229 *** Use the X window system
231 [[./images/x-menu.png]]
233 The function [[sym:yas-x-prompt][=yas-x-prompt=]] can be used to show a popup menu for you to
234 select. This menu will be part of you native window system widget, which
237 - It usually looks beautiful. E.g. when you compile Emacs with gtk
238 support, this menu will be rendered with your gtk theme.
239 - Your window system may or may not allow to you use =C-n=, =C-p= to
241 - This function can't be used when in a terminal.
243 *** Minibuffer prompting
245 [[./images/ido-menu.png]]
247 You can use functions [[sym:yas-completing-prompt][=yas-completing-prompt=]] for the classic emacs
248 completion method or [[sym:yas-ido-prompt][=yas-ido-prompt=]] for a much nicer looking method.
249 The best way is to try it. This works in a terminal.
251 *** Use =dropdown-menu.el=
253 [[./images/dropdown-menu.png]]
255 The function [[sym:yas-dropdown-prompt][=yas-dropdown-prompt=]] can also be placed in the
256 [[sym:yas-prompt-functions][=yas-prompt-functions=]] list.
258 This works in both window system and terminal and is customizable, you
259 can use =C-n=, =C-p= to navigate, =q= to quit and even press =6= as a
260 shortcut to select the 6th candidate.
264 See the documentation on variable [[sym:yas-prompt-functions][=yas-prompt-functions=]]