Cannot find a variable that sets the "abbreviation" of a library name/prefix

Cannot find a variable that sets the "abbreviation" of a library name/prefix

[Ruijie Yu via Emacs development discussions.]

Hello,

I'm definitely not dreaming, but I saw a variable from a patch somewhere
the other day, that works like this:

When one sets this variable to an alist of full-name (string) ->
short-name (string), the file itself defines symbols with short names,
while the loader pretends they are using the long names.  For example,
lets say the full name is "library", and short name is "lib".  Then, you
can define functions or variables like this:

```emacs-lisp
;; library.el --- example
(defvar lib-foo nil)
(defun lib-bar () t)

(provide 'library)
;; Local variables:
;; i-dont-know-what-this-variable-is-called: (("library" . "lib"))
;; End:
```

And the outside Elisp environment, when loading this file, now pretends
that the variable `library-foo' and the function `library-bar' are
defined.

```emacs-lisp
(require 'library)
(progn library-foo (library-bar))
```

However, when I search for "abbrev" using M-x apropos-command, I cannot
find anything.  Have I actually been dreaming?  Thanks.

-- 
Best,


RY

[Please note that this mail might go to spam due to some
misconfiguration in my mail server -- still investigating.]

Re: Cannot find a variable that sets the "abbreviation" of a library name/prefix

[Eli Zaretskii]

> Date: Sat, 29 Apr 2023 22:47:49 +0800
> From:  Ruijie Yu via "Emacs development discussions." <emacs-devel@gnu.org>
> 
> I'm definitely not dreaming, but I saw a variable from a patch somewhere
> the other day, that works like this:
> 
> When one sets this variable to an alist of full-name (string) ->
> short-name (string), the file itself defines symbols with short names,
> while the loader pretends they are using the long names.  For example,
> lets say the full name is "library", and short name is "lib".  Then, you
> can define functions or variables like this:
> 
> ```emacs-lisp
> ;; library.el --- example
> (defvar lib-foo nil)
> (defun lib-bar () t)
> 
> (provide 'library)
> ;; Local variables:
> ;; i-dont-know-what-this-variable-is-called: (("library" . "lib"))
> ;; End:
> ```
> 
> And the outside Elisp environment, when loading this file, now pretends
> that the variable `library-foo' and the function `library-bar' are
> defined.
> 
> ```emacs-lisp
> (require 'library)
> (progn library-foo (library-bar))
> ```
> 
> However, when I search for "abbrev" using M-x apropos-command, I cannot
> find anything.  Have I actually been dreaming?  Thanks.

You are talking about read-symbol-shorthands, I think.

Re: Cannot find a variable that sets the "abbreviation" of a library name/prefix

[João Távora]

On Sat, Apr 29, 2023 at 3:58 PM Ruijie Yu via Emacs development
discussions. <emacs-devel@gnu.org> wrote:
>
> Hello,
>
> I'm definitely not dreaming, but I saw a variable from a patch somewhere
> the other day, that works like this:
>
> When one sets this variable to an alist of full-name (string) ->
> short-name (string), the file itself defines symbols with short names,
> while the loader pretends they are using the long names.  For example,
> lets say the full name is "library", and short name is "lib".  Then, you
> can define functions or variables like this:

This would be read-symbol-shorthands.  Look in up in the manual and see
the following for a practical example of a library that uses it:

https://github.com/joaotavora/beardbolt/edit/master/beardbolt.el

> And the outside Elisp environment, when loading this file, now pretends
> that the variable `library-foo' and the function `library-bar' are
> defined.

It's actually the other way round.  It's `lib-foo` and `lib-bar` that
were never really names of symbols.  They were always `library-foo` and
`library-bar` underneath, they're just written in abbreviated shorthand
form.

It's not only when loading the file from the "outside": it's also when
compiling definitions from inside, and looking up ElDoc documentation,
etc.

João