Re: [gentoo-dev] [RFC] Policy for migrating library consumers to subslots

[Davide Pesavento]

On Fri, Sep 27, 2013 at 4:44 PM, Michał Górny <mgorny@g.o> wrote:
> Dnia 2013-09-26, o godz. 17:24:49
> Davide Pesavento <pesa@g.o> napisał(a):
>
>> On Thu, Sep 26, 2013 at 4:04 PM, Kent Fredric <kentfredric@×××××.com> wrote:
>> >
>> > On 26 September 2013 19:53, Michał Górny <mgorny@g.o> wrote:
>> >>
>> >> How do we handle packages which install multiple libraries? I'm afraid
>> >> forcing such a policy and/or hurrying developers to adapt will only
>> >> cause more of poppler-like issues to occur.
>> >
>> >
>> > Can you give a an example package which:
>> >
>> > - installs multiple libraries
>> > - has an ABI that may change for only one of those libraries
>> > - it is sane / plausible to expect one downstream dependent *not* to
>> > forcibly rebuild as a result of a chane in one of those libaries
>> > - it is sane / plausible to expect a different downstream to forcibly
>> > rebuild as a result of changes in one of those libraries
>> >
>>
>> dev-python/PyQt4
>>
>> Each module is a separate library, and each has its own ABI that can
>> change independently from the others. Downstream projects that rely
>> only on PyQt4's python API are not affected by ABI changes, but those
>> (very few) that link against one or more modules (e.g. kde-base/pykde4
>> I think) must be rebuilt.
>
> How often does ABI of pyqt4 libraries change in such a way that rebuild
> of pykde4 is not required?

Practically never (see below).

>
> Looking at the dep:
>
>>=dev-python/PyQt4-4.9.5[${PYTHON_USEDEP},dbus,declarative,script(+),sql,svg,webkit,X]
>
> I'd think it's fairly rare when only the libraries not listed above
> change ABI without any of the remaining ones changing it.
>

Actually, most PyQt4 libraries never changed their ABIs since the
initial 4.0 release, so yes, it's "fairly rare" :)
That's also one of the reasons why I never bothered to add a subslot to PyQt4.

Thanks,
Davide