Why c++ not support placement delete

[XHengDF]

something like this:
T *p = new(Alloc&)T;
delete(Alloc&) p;
is that will take problems!
now we could use Dealloc(Alloc&, void *p);
in the bs's tech Faq, i could not find the reason why not take the
placement delete to the language!

thinks;

 

[benben]

something like this:
T *p = new(Alloc&)T;

Alloc& cannot be a pointer. Perhaps you mean &Alloc?

delete(Alloc&) p;
is that will take problems!
now we could use Dealloc(Alloc&, void *p);
in the bs's tech Faq, i could not find the reason why not take the
placement delete to the language!

thinks;

a placement new doesn't really allocate memory. It simply calls the
constructor.

To destroy an object without deallocating the memory, simply call the
destructor:

void* rawptr = malloc(sizeof(T));
T* p = new(rawptr) T;
p->~T(); // destruction, but not deallocation
free(rawptr); // deallocation

Regards,
Ben

 

[Tomás]

posted:

something like this:
T *p = new(Alloc&)T;
delete(Alloc&) p;
is that will take problems!
now we could use Dealloc(Alloc&, void *p);
in the bs's tech Faq, i could not find the reason why not take the
placement delete to the language!

thinks;

I've often thought that "placement new" is a bad name for it, because
it's got nothing to do with the allocation of memory.

All it does is call the constructor.


-Tomás