Qt-interest Archive, May 2008
Re: QMap::operator[]
Message 1 in thread
The reason for the change is that all of the containers in QT4 are reference
counted and have private data pointers to the real data such that:
sizeof(Container) == sizeof(void *).
this means that things like: QMap<QString> a = b; is just a copy of a
pointer and increment of a refernce count. Pretty much just as cheap as a
reference (which is just a copy of a pointer).
At least that's my understanding of it.
Evan Teran
Vladimir Romanovskiy wrote:
> Hi,
>
> In Qt 3.3.8 the const operator QMap::operator[] returned a constant
> reference:
>
> const T & QMap::operator[] ( const Key & k ) const
>
> In 4.3.4 the same operator now returns a constant object:
>
> const T QMap::operator[] ( const Key & key ) const
>
> Why was changed that important operator?
> Temporary object that created with this operator results in hidden errors!
>
> Thanks,
> Vladimir
>
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