bug#60032: 30.0.50; [WISH] Customizing Info directories

[Ihor Radchenko <yantar92@posteo.net>]

Eli Zaretskii <eliz@gnu.org> writes:

> Please describe your use case, because I don't think I see why another
> variable would be needed.  I guess you have INFOPATH defined (by
> someone who is not you?), but you don't like its value or something?
> It's not clear which problems you are trying to solve.

We had a user confused about how to force Emacs info command use Org
manual from git repo:
https://list.orgmode.org/87359jcuoi.fsf@localhost/T/#mde65bfe981036a6ff2e1faa750670d9af648bad8

The user attempted to customize `Info-default-directory-list' and got
surprised that it was ignored.

Upon my further investigation, `Info-default-directory-list' is indeed
ignored when INFOPATH is set by OS.

I also had a similar confusion and gave up customizing Info directories
at some point. Not because it is not documented, but because the setting
is so unusual that I do not think about finding it.

> In general, I can say 2 things, which I'm sure you already know:
>
>   . environment variables can be set inside Emacs
>   . you can hack Info-directory-list in any number of ways, and do
>     whatever you want with it, in Lisp
>
> While the above two methods are not exactly what I'd suggest to an
> Emacs an Info newbie, I definitely can see you using them.  So again,
> I'm unsure what kind of awkwardness is bothering you.  Please
> elaborate.

I do agree that it is possible to set Info directories to desired value.
However, `Info-default-directory-list' being ignored is rather
surprising, especially given that setting the other defcustom
(`Info-additional-directory-list') does not allow overriding system
settings.

Changing `Info-directory-list' is difficult because one needs to run
(info-initialize), which can only be found by reading the source code.

Changing environment variables is something I never ever needed to
customize Emacs' behaviour. Once I see it, my thinking goes: "Surely,
there should be some custom variable.", but no such variable exists.

Conclusion: Current customization state is not a game breaker, but
something I find confusing. That's why WISH.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
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