[Development] How to include Standard Library headers from Qt ones?

Corentin corentin.jabot at gmail.com
Sun Apr 16 18:32:53 CEST 2017

I think that part of the issue is that the way the STL should be treated is
a bit of a polarizing issue.
Of course, there are technical considerations, such as some STL
implementations being lacking on older platforms, but mostly Qt and the STL
have some overlaps, and people can't agree on how to handle said overlaps.

I personally consider that the STL is as much part of C++ than the core
language and any api should therefore be as much compatible with it as
possible. Redundant algorithms & utilities ( mutex, shared pointer, etc ),
should probably not exist at all at this point, though they used to make

As such, Qt containers should work properly with any STL types, and Qt
types should work well with the STL constructs, containers, types and
Most people use Qt as a framework and play by Qt's rules, but for others Qt
may just be the UI layer, an other library in the stack. Both use cases
should be catered to.

More on point:
   * You don't actually need to include anything from the STL to implement
   * For qHash, maybe one or more qt_stl.h headers that would include the
required stl headers. Forward declare when possible ( probably not often,
sadly ). Compilations times may, for the time being, be an issue but I
don't think Qt can or should work around them.

I would also prefer a solution that is independent of the order of the

Since the flurry of last years' microoptimizations in the QString and
> algorithm area had measurably negative impact on me (like time I had to
> spend to work around SC breakages), but no measurable positive impact
> (should I have witnessed any performance gains?) I reserve the right to
> be sceptical here, unless something resembling a proof of the opposite
> shows up.

Micro-optimizations on such low level classes are always worth it.

> Andre'
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> Development at qt-project.org
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