>>just look at the include files:

 

i looked at the header, but got a little confused.

i don't see how you can call a destruct of a a memory space that still exists. ie a C version of a vector.

 

shared_ptr<int> list[1024];

int n = 0;

 

// add an item

shared_ptr<int> newItem(new int(1));

list[n++] = newItem;

 

// remove the tail item

n--;

// destructor never called

 

is it possible to call a destructor of an object that exists?

what then happens then the object goes out of scope? the destructor will be called twice.

 

(or maybe i am completely missing the point)

 

BTW: not sure if above code compiles (did it in my head)

 

On 7/10/06, Boris Breidenbach <Boris.Breidenbach@physik.uni-erlangen.de> wrote:

On Mon, Jul 10, 2006 at 03:58:19PM +1000, bringiton bringiton wrote:
> This question is based on curiosity. How does std::vector::pop_back() call
> the destructor of the item getting removed?
>
> i understood std::vector to be a contigious array of memory, therefore an
> item's memory does not go out of scope when being popped. ie the item goes
> out of scope when the entire array goes out of scope.

just look at the include files:

bits/stl_vector.h says:
void
     pop_back()
     {
       --this->_M_impl._M_finish;
       std::_Destroy(this->_M_impl._M_finish);
     }

so the destructor is called in std::_Destroy.  Which can be found in
bits/stl_construct.h:
/**
  * @if maint
  * Destroy the object pointed to by a pointer type.
  * @endif
  */
template<typename _Tp>
   inline void
   _Destroy(_Tp* __pointer)
   { __pointer->~_Tp(); }

It just calls the destructor.

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