Re: Trying to fix IBus

[Chris Marusich <cmmarusich@gmail.com>]

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Ricardo Wurmus <rekado@elephly.net> writes:

> Chris Marusich <cmmarusich@gmail.com> writes:
>
>> Ricardo Wurmus <rekado@elephly.net> writes:
>>
>>> NixOS encountered the same problem:
>>>
>>>     https://github.com/NixOS/nixpkgs/pull/14568
>>>
>>> I don’t like their solution to set a variable NIX_PROFILES and let GTK
>>> look for immodule files in each of the directories.
>>
>> Why don't you like their solution?  Why do you believe that your
>> proposed solution is better than their solution?  We should make sure to
>> choose the best solution available, and right now I'm not sure which one
>> is better.
>
> I find it very inelegant to ask users to specify a list of directories
> containing profiles.  A mechanism like that also seems like a hack to
> me, and I’m afraid that we would begin to rely more and more on this to
> “solve” other problems.
>
> Splitting a variable that GTK is already using anyway into two different
> versions just seems a lot cleaner to me.  The variable won’t even need
> to be exposed to most users; we could set it automatically when
> generating profiles.
>
> Eventually this will disappear once the GTK devs retire support for
> separate input method modules (I guess this would make IBus a hard
> dependency on GNU systems).  At that point we can easily drop our
> patches and the profile hook; a generic GUIX_PROFILES variable, on the
> other hand, would be more difficult to deprecate if it becomes more
> popular (as it has a much broader scope).

That makes sense.  I think these are good reasons to favor your solution
instead of the NixOS solution.  I think your plan is good.

>>> Instead, I think we should patch both GTK versions to respect
>>> GUIX_GTK2_IM_MODULE_FILE and GUIX_GTK3_IM_MODULE_FILE, and generate
>>> the immodule cache files in a profile hook.
>>>
>>> We did something similar before with GUIX_GTK2_PATH and GUIX_GTK3_PATH.
>>
>> I believe you are referring to this thread:
>>
>> https://lists.gnu.org/archive/html/guix-devel/2015-12/msg00046.html
>>
>> Did that patch actually get committed?  If so, why didn't it solve the
>> problem?  I've read all the relevant discussions I could find [1], and
>> it isn't clear to me why we need to do what you're suggesting ("patch
>> both GTK versions to respect GUIX_GTK2_IM_MODULE_FILE and
>> GUIX_GTK3_IM_MODULE_FILE, and generate the immodule cache files in a
>> profile hook") if we've already committed the patch presented in the
>> thread above.
>
> Yes, that patch got committed and it actually solved a problem.  It is a
> different problem, though.  GTK really assumes modules to be in one
> place, which means that with immutable directories we have no other way
> to make things work.

I see.  I guess I just wasn't familiar with the other issue.  Thank you
for explaining.

One last thing: it seems that the NixOS devs' choice of solution was
influenced by a desire not to require users to rebuild programs that
were previously installed in their profiles [1].  They almost chose a
solution like the one you are proposing, but they changed their minds to
avoid requiring users to rebuild existing programs in their profiles.
GuixSD is still Beta, so I don't think that's an issue for us at all.

[1] See abbradar's comment on April 8th, 2016:

https://github.com/NixOS/nixpkgs/pull/14417#issuecomment-207362530

"This patch would break all such software that uses old (unpatched)
GTK+3."

This appears to be the primary reason why they chose to patch GTK+2 and
GTK+3 to search NIX_PROFILES for an immodules.cache file instead of
patching it to use separate environment variables for GTK+2 and GTK+3.

-- 
Chris

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