Is there a way to expand snippets without pressing tab or any trigger key at all?

I guess you could try something like

(defun my-yas-try-expanding ()
  (when yas-minor-mode (yas-expand)))
(add-hook 'post-command-hook #'my-yas-try-expanding)

I'm coming from vim and UltiSnips where you can specify in the snippet definition whether a particular snippet should be auto-expanded. Would it be feasible to add such a feature here?

I like auto-expansion, but making it global would either limit one's ability to write "normal" text or it would demand some really complex snippet keys lest it is accidentally typed (e.g. auto-expanding the latex figure snippet "fig" would make it hard to write plain text).

@korsbo You can use the condition system for this. Something along the lines of

(defun my-yas-try-expanding-auto-snippets ()
  (when yas-minor-mode
    (let ((yas-buffer-local-condition ''(require-snippet-condition . auto)))
      (yas-expand))))
(add-hook 'post-command-hook #'my-yas-try-expanding-auto-snippets)

Then put # condition: 'auto in the yasnippets you want to be able to expand automatically.

Nice one, thanks!

(defun my-yas-try-expanding-auto-snippets ()
  (when yas-minor-mode
    (let ((yas-buffer-local-condition ''(require-snippet-condition . auto)))
      (yas-expand))))
(add-hook 'post-command-hook #'my-yas-try-expanding-auto-snippets)

Then put # condition: auto in the yasnippets you want to be able to expand automatically.

I am trying this and getting
[yas] Error in condition evaluation: Symbol’s value as variable is void: auto
# condition: auto is already in the snippet I want to spand.

EDIT:
I think problem was syntax. Changed
require-snippet-condition . auto
to
require-snippet-condition.auto
and it worked. Thanks!

I am trying this and getting
[yas] Error in condition evaluation: Symbol’s value as variable is void: auto
# condition: auto is already in the snippet I want to spand.

Sorry, I made a mistake, it should be #condition: 'auto (with a quote), in the snippets to expand.

require-snippet-condition.auto
and it worked.

If this works, it's only by accident.

Sorry, I made a mistake, it should be #condition: 'auto (with a quote), in the snippets to expand.

Aaah that fixes everything.

If this works, it's only by accident.

Yes, it was working but still displaying the error in logs, but working.

Just in case anyone else may find it useful: I had trouble using this in spacemacs since yas-minor-mode does not seem to be immediately defined. My fix was just a minor tweak of the above, inserted to the user-config function.

  (defun my-yas-try-expanding-auto-snippets ()
    (when (and (boundp 'yas-minor-mode) yas-minor-mode)
      (let ((yas-buffer-local-condition ''(require-snippet-condition . auto)))
        (yas-expand))))
  (add-hook 'post-command-hook #'my-yas-try-expanding-auto-snippets)

I'm finding this very useful. Could this be added to the main codebase rather than as a user configuration?

I'm finding this very useful. Could this be added to the main codebase rather than as a user configuration?

Pending in #1048. I'll probably make a minor bug fix release in a month or so, before merging that.

Just in case anyone else may find it useful: I had trouble using this in spacemacs since yas-minor-mode does not seem to be immediately defined. My fix was just a minor tweak of the above, inserted to the user-config function.

  (defun my-yas-try-expanding-auto-snippets ()
    (when (and (boundp 'yas-minor-mode) yas-minor-mode)
      (let ((yas-buffer-local-condition ''(require-snippet-condition . auto)))
        (yas-expand))))
  (add-hook 'post-command-hook #'my-yas-try-expanding-auto-snippets)

Thanks for this super useful function.

Just a question. How do you could expand snippet only in certain modes? (e.g. issue #990 )

In the mentioned issue, the example is having something like this

# -*- mode: snippet -*-
# name: Parenthesis
# binding: ()
# key: ()
# --
\left($1\right)

and expand this text

The parenthesis are $()$

into this

The parenthesis are $\left(<CURSOR HERE>\right)$

However, the idea is to do it typing no other character apart from ().

Thanks for your help.

@maikol-solis here's what I use. I think it's what you're looking for.

# -*- mode: snippet -*-
# name: parentheses
# key: ()
# condition: (and (texmathp) 'auto)
# --
\left($1\right)$0

I have this filed under snippets/latex-mode so that it's expanded in latex mode only when editing a math environment. Note that you can also get this to work in other modes selectively. For instance, I have a .yas-parents file for org-mode so that this also works when I'm editing latex math in an org buffer.

This an example of using the condition system.

Also, a small nitpick. In the issue you reference you ask about only expanding inside a math environment. However, your recent question asks about only expanding within certain modes. To say mode is a bit misleading here. I don't believe there is any mode associated with being inside a tex math environment (though correct me if I'm wrong), texmathp is simply a function that identifies whether you're inside a tex math enviro. If your question were truly about mode-specific expansion, you'd want to look at the organization section of the documentation, but I don't think that's the part that confuses you.

@maikol-solis here's what I use. I think it's what you're looking for.

# -*- mode: snippet -*-
# name: parentheses
# key: ()
# condition: (and (texmathp) 'auto)
# --
\left($1\right)$0

I have this filed under snippets/latex-mode so that it's expanded in latex mode only when editing a math environment. Note that you can also get this to work in other modes selectively. For instance, I have a .yas-parents file for org-mode so that this also works when I'm editing latex math in an org buffer.

This an example of using the condition system.

Brilliant! This is exactly what I want it.

Also, a small nitpick. In the issue you reference you ask about only expanding inside a math environment. However, your recent question asks about only expanding within certain modes. To say mode is a bit misleading here. I don't believe there is any mode associated with being inside a tex math environment (though correct me if I'm wrong), texmathp is simply a function that identifies whether you're inside a tex math enviro. If your question were truly about mode-specific expansion, you'd want to look at the organization section of the documentation, but I don't think that's the part that confuses you.

You are completely right. The idea is auto expand the triggers only when there is a math environment (inline or displayed) inside a latex document.

Your solution is exactly what I intend to do.

Thanks for the help.

I found a minor glitch with this feature.

#1048 (comment)

Hello. This little function is very interesting.
If I put it in my init.el, I get an error :
Error in post-command-hook (my-yas-try-expanding-auto-snippets): (void-variable yas-minor-mode)

Whereas if i force the evaluation once it is fully started, I get no error.

Do I have to add something, like waiting for something to be loaded before evaluating the function ?

Thanks for the help !