Re: [gentoo-dev] Using LINGUAS

[Alex Xu]

On 21/07/14 12:23 AM, Thomas Kahle wrote:
> Hi,
>
> the OCR software tesseract has many different plugins for
> language packs used for OCR for different languages.  The ebuild
> uses the LINGUAS variable to pass the choice of which packages to
> install to the user.
>
> A reverse dependency is app-text/pdfsandwich which roughly puts
> OCR'ed text in a scanned pdf.  Since it uses tesseract it
> supports exactly those languages that tesseract supports.
>
> Should its ebuild have LINGUAS use flags and then depend on
> tesseract with at least those flags set?
>
> While it seems consistent to put the LINGUAS choice in the most
> user facing package, in this case I would actually not put it in
> here.  It would introduces a point of failure and maintenance
> work for the each tesseract upgrade (since the language set
> slightly changes from time to time).  A typical user would set
> LINGUAS in her make.conf anyway.  In this case the same choice
> applies to both packages anyway.  Maybe an einfo is sufficient to
> inform the user it?
>
> Cheers,
> Thomas
>

there are two possible scenarios here.

1. the dependency is COMPILE TIME (ABI, API, whatever). in this
scenario, the depender *must* have appropriate LINGUAS, even if that
means copying and pasting from the dependee. this is necessary for
correct rebuilding, and everything else associated with automagic deps.

2. the dependency is RUN TIME. in this scenario, the case is the same
with all other runtime USE dependencies; that is to say, the correct
solution is USE_RUNTIME or something along those lines. [0] here, I
would say that einfo is superior to copying IUSE, since these flags
should be set globally anyways to make sense.


[0] please no bikeshedding on whether to call it RUNTIME_USE or ǝsn‾ǝɯıʇunɹ.