Re: executable-set-magic update

["Andrew L. Moore" <slewsys@gmail.com>]

> On Jul 24, 2017, at 2:22 PM, Andrew L. Moore <slewsys@gmail.com> wrote:
> 
>>> It would also be nice if `executable-set-magic’ were supported beyond
>>> `sh-set-shell’ (in lisp/progmodes/sh-script.el), so I implemented
>>> a minor mode that adds the following hook to find-file:
>>> 
>>> (defun script-set-magic ()
>>>  "Look up interpreter associated with current major mode in
>>> `script-set-magic-alist' and call `executable-set-magic'."
>>>  (let ((interpreter (alist-get major-mode script-set-magic-alist)))
>>>    (if interpreter (executable-set-magic interpreter)))
>>>  )
> 
>> Stefan Monnier wrote:
>> Doesn't this add a #! to every file using modes like
>> js/ruby/awk/perl/python/...?
>> 
>> In multi-file programs, only the main file needs a "#!", so I don't
>> understand why adding #! to all files would make sense.
> 
> Stefan,
> Sorry I missed your comment.  Yeah, script libraries don’t use magic numbers, so
> I updated the minor mode with a variable that allows skipping files in “project”
> directories.  And since the minor mode leverages executable-set-magic, it's been
> renamed `executable-set-magic-mode’:
> 
> https://github.com/slewsys/emacs-extensions/blob/master/executable-set-magic.el
> 
> The current implementation searches for a “project root” in the file path
> by brute force. Hopefully that can be updated with something more elegant.
> 
> In the mean time, function `executable-set-magic' only seems to be leveraged
> by lisp/progmodes/sh-script.el for shell scripts.  So an alternative to
> extending it might be removing it, e.g., to an external library.
> -AM

Oops, the “project root” search was ugly too.  Reversing the order of the functions,
hopefully it’s just inelegant now.
-AM