2

I want to define a yasnippet for shell-script mode that would insert a chunk of text whose content depends on the setting of the sh-shell variable.

Since the possible different text insertions are several lines long, and are quite different from each other, so doing this with conditional fields of the form

${N:`(case sh-shell (zsh  "foo")
                    (bash "bar")
                    (sh   "baz")
                    (t    "frobozz"))`}

...would all but eliminate the convenient formatting one this sort of template for.

EDIT: To clarify: the code above is not useful to me, because I need to insert multi-line formatted text, not little, one-word strings like "foo", "bar", etc.


If I were to use an unholy mix of Elisp and bash to represent what I'm looking for, this is how I'd represent it:

`(case sh-shell (zsh <<EOZSH)
zsh version
    of
    snippet
    looks
    like
    this
EOZSH
                   (bash <<EOBASH)
bash version of snippet looks like this
EOZSH
                   (sh   <<EOSH)
sh
 version
  of
   snippet
    looks
     like
      this
EOSH
                   (t    <<EODEFAULT)
default version
  of snippet
    looks
    like
    this
EOSH
)`

IOW, the snippet would consist of a single embedded Elisp case expression, where the key of each key-value pair is a possible value of sh-shell, and the value is a (formatted) snippet/template; I've represented the latter using (totally invalid) heredoc notation.


Is there a (syntactically sound) way to implement this idea?

  • I don't understand what's wrong with the first version. The multi-line formatting is only visible in the snippet definition, where arguably it's a good thing as it makes it easy to read your code. The expansion is still just one line long. I think case won't work though, if sh-shell takes string values. case compares via eql, which only returns true if the arguments are the same lisp object, not if they are different objects with the same value. – Tyler Jan 26 '17 at 23:33
  • @Tyler: sorry for the confusion; I've edited my post to clarify things. – kjo Jan 27 '17 at 0:35
  • You can still use the same code, replacing foo etc with a multi-line string. Unless you need to dynamically manipulate the indentation of your inserted text, I don't know what a better approach would be. – Tyler Jan 27 '17 at 1:04
1

You can call any elisp function from your snippet definition, so if you can use a helper function defined in your init file to keep the snippet file tidier. In your .emacs or .emacs.d/init.el:

(defun snippet-helper ()
  (cond ((string-equal sh-shell "zsh") "foo")
        ((string-equal sh-shell "bash") "bar")
        ((string-equal sh-shell "sh") "baz")
        (t "foo")))

(note that the case form doesn't work when comparing strings that aren't the same object, so I used cond instead).

Then your snippet becomes:

# -*- mode: snippet -*-
# name: hhh
# key: hhh
# --
${N:`(snippet-helper)`}
  • Actually, this doesn't work if your replacement strings contain multiple spaces to align the different lines. Extra spaces get removed by a call to (yas--indent snippet). Not sure how to fix this yet. – Tyler Jan 27 '17 at 22:44

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