[Development] Use of std::function in Qt API

[Thiago Macieira]

On terça-feira, 14 de março de 2017 09:01:25 PDT Ville Voutilainen wrote:
> Ahem, it's not like there weren't qualms about it, but doing it for
> std::string and std::list
> was eventually necessary. The libstdc++ developers (including myself)
> spend fair amounts
> of time and energy trying to avoid abi breakage, including abi
> breakage in downstream libraries.

I know, and we're grateful for 7 years of no breakage. It was good while it 
lasted.

But then it happened, as we all knew it would. And then it happened again, in 
a separate release, instead of everything in one release.

The cxxabi people also keep a document about a v2 of the ABI itself, so that 
will happen some day.

> > What we have to ask ourselves is whether we want to say that is not our
> > problem. For example, the std::string breakage caused any application or
> > library that used it in its API to need to be recompiled. Besides Qt,
> > there
> > aren't many libraries that avoid it. So if the underlying C++ Standard
> > Library breaks ABI, should we try to work around it? Or should we punt
> > the problem to the user?
> 
> I don't know. What do our users want? How big a problem would it be for
> them?

Right. See also the libc++/libstdc++ mix, which Linux distributions have not, 
after years of shipping libc++, done properly. So it seems like mixnig is not 
a desired use-case.

Given that, I'm beginning to think that we should change our policy.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center