[Development] QStringLiteral vs QLatin1String , foreach vs for range

André Somers andre at familiesomers.nl
Wed Jan 20 08:12:58 CET 2016

Op 20/01/2016 om 06:47 schreef Thiago Macieira:
> On Wednesday 20 January 2016 05:20:36 Kevin Kofler wrote:
>> Thiago Macieira wrote:
>>> foreach copies; ranged for doesn't.
>> … unless you try to use it on a non-const Qt container with usage count >1,
>> then it will even deep-copy (detach) it! (I know you know this, but you
>> should warn people about it.) So you need to be very careful about what you
>> pass to ranged for.
> Indeed.
> But his is the argument that convinced me: with foreach and Qt containers, you
> usually get the runtime performance you want, but it costs in dead code since
> the deep-copy code will be present (at least until we can get rid of the
> unsharable flag). With ranged for plus qAsConst, there's no copy code
> generated.
> So instead of:
> 	foreach (auto x, container)
> You'll write:
> 	for (auto x : qAsConst(container))
> or if you know it's already const, you can skip the qAsConst part.
> This is no more and no less readable, but is more explicit about what it does.
Where is this qAsConst coming from? When was it introduced? Where is it 

I can't find it in my Qt documentation.


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