[Qt-interest] Strange (as for me) QByteArray behavior

[Thiago Macieira]

On Wednesday, 8 de December de 2010 09:07:52 Konrad Rosenbaum wrote:
> On Wednesday 08 December 2010, Ivan Kharin wrote:
> > > QByteArray tmp = username.toAscii();
> > 
> > const QByteArray &tmp = username.toAscii(); // avoid copy: const ref to
> > function result == //   keep automatic variable intact until end of
> > scope
> 
> I don't think this can work reliably. C++ is not a garbage collected
> language, the reference becomes invalid immediately after the semicolon.

That's not correct. The above is perfectly valid C++.

I've seen experimental compilers choke on it though (clang). But that's a 
compiler bug and it got fixed.

> Besides: it is unnecessary. QByteArray is implicitly shared - so very
> little data is actually copied.

That's also true. It's just a reference counting up an down.

With C++0x, we'll probably do a move constructor too.

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Senior Product Manager - Nokia, Qt Development Frameworks
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