Re: are container elements on the stack or heap
* Michiel.Salters@tomtom.com:
Alf P. Steinbach wrote:
* Anjo Gasa:
Let's say I have:
std::vector<Object> rgObjects;
rgObjects itself is declared as a local variable and hence on the
stack. But what about as I add elements to rgObjects:
Object newObject( 3, 4 );
rgObjects.push_back( newObject );
newObject itself isn't placed on the vector, rather the copy
constructor is called, and an object copied with its values is placed
on the vector. Does this new instance of Object reside on the stack or
the heap.
... the copy might reside in dynamically allocated memory or not,
depending on the implementation of std::vector, the current size of the
vector, and e.g. the phase of the moon.
I don't think the default allocator has such liberty (and Anjo didn't
override it)
so the copy will reside in memory dynamically allocated by the default
allocator.
That's news to me.
It would mean that the standard disallows small-size optimization using
a fixed buffer, or that there is a fundamental difference in those
requirements for std::basic_string and std::vector (apart from
contigousness, which now is solved).
I don't think there is such a difference -- and if there is, it would
be a defect in the standard.
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