Re: [PATCH v2] .dir-locals.el: Automatically set the GEISER-GUILE-LOAD-PATH variable.

[Maxim Cournoyer]

Hello Miguel!

Miguel Ángel Arruga Vivas <rosen644835@gmail.com> writes:

> Hello, Maxim!
>
> Thanks for your effort in this, some comments with the quotes for
> context.

Thanks for your comments, they've already made this proposed change much
better!

> Maxim Cournoyer <maxim.cournoyer@gmail.com> writes:
>>> This fails if geiser-guile-load-path does not exist (void-variable).
>>> The cleanup removes other guixes, isn't it?  I suggest making the
>>> variable buffer-local and forget about hard-coded names. :-)
>>
>> That's a good suggestion!  I toyed with it and it's a bit tricky but I
>> think the v2 patch I'll send as a follow-up does the trick.  My concern
>> was also supporting when a user has previously set
>> geiser-guile-load-path in their .emacs init file, e.g.:
>>
>> (setq geiser-guile-load-path (list (expand-file-name "~/src/guix")
>>                                    (expand-file-name "~/src/shepherd")))
>>
>> That would mean their entries don't get cleaned up (it seems this
>> doesn't matter in my latest tests with the v2 patch though!).
>
> That cleanup seems to me responsibility of that .emacs maintainer
> instead of something to take into account in .dir-locals. ;-)

Indeed, it could be seen that way!  The good news is that it doesn't
seem to cause any problems anyway, should they forget an entry for Guix
there.

>>> (eval . (setq guix-directory
>>>           (locate-dominating-file default-directory ".dir-locals.el")))
>>> (eval . (when (boundp 'geiser-guile-load-path)
>>
>> This check makes it so that if geiser-guile-load-path is not already
>> defined, nothing happens.  It is likely that this is the case, as when
>> relying on just Geiser's autoloads, it is not loaded.  The user would
>> have to either set explicitly before hand or call (require
>> 'geiser-guile), which we can't rely on.  But we can drop this check.
>
> You're right, as you can only bind the keys and enable it when used, not
> at file load as I do, great catch. :-)
>
>> One thing that worried me was the %load-compiled-path not appearing in
>> the order defined from guile-geiser-load-path, but in my latest tests as
>> mentioned above it didn't matter.
>
> With the right directories (meaning no-conflicts between modules) it
> shouldn't matter, but it's weird.  Looking into geiser-guile.el the load
> path is provided to guile through -L parameters in
> geiser-guile--parameters, and the extra path for Geiser code is added
> with geiser-guile--set-geiser-load-path (that's why it is not added to
> %load-compiled-path)...  I'd have to check Guile to be sure why are the
> differences, but they seem harmless.

OK, thank you for investigating!

>> +               (unless (fboundp 'geiser-guile-load-path)
>> +                 (defvar geiser-guile-load-path '()))
>
> This checks the function definition, not the variable, as Emacs Lisp has
> two separate namespaces.

Oops, good catch!

>> I ended up using `cl-pushnew' here instead of push, as otherwise
>> repeated entries were accumulated.
>
> I wanted to avoid exactly that check, as the variable should end up with
> duplicated entries only when you call it twice from the same buffer, how
> could that happen?
>
>> +               (make-local-variable 'geiser-guile-load-path)
>> +               (cl-pushnew root-dir* geiser-guile-load-path
>> +                           :test #'string-equal)))))
>
> If there is some way this may happen, then this call is OK, but I'd try
> to stay with a cheaper push unless it's really needed, as O(1) < O(n),
> for almost every n. :-)

The way I could easily trigger this was to open a dired buffer, and
hitting 'g' to refresh its contents.

> Again, thank you very much for taking care of this, as it would make
> life easier for everybody of us who uses Geiser.

I'm glad to read it! :-)

I'll be sending a v3 with the fboundp woopsie above fixed.

Maxim