Re: Delete without calling destructor?
* Tom1s # hilidhe:
Alf P. Steinbach:
If you know the exact size used for the original allocation you could
perhaps use ::operator delete.
However I recommend, instead, to not do what is most likely premature
optimization.
And anyway, if measurements show you really need to avoid those
"needless" allocations and deallocations, define operator new and
operator delete for the class, and/or use an allocator more suitable
for this particular situation than the built-in one.
The constructor of the class in question has code that exists in no
order member function of the class.
I need to run this code a couple of times a second, but I don't want to
fragment the heap (or have the overhead of allocating memory each time).
Also, when the algorithm's finished, I'd like to be able to deallocate
the memory of the object which already had its destructor invoked.
How would I use operator delete? Something like the following?
::operator delete (p);
(Do you need to write "operator"? Is there any difference between
::new(p) T;
and:
::operator new(p) T;
)
You can't write the latter.
"operator new" is a function, more specifically an allocator function.
"new" on its own is, OTOH., a syntactical construct that except for the
placement form and except for possible allocation failure ends up
calling (1) some "operator new", (2) a constructor, and (3) if the
constructor fails via an exception, the corresponding "operator delete".
Cheers, & hth.,
- Alf
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