Re: using delete expression on global operator new allocated memory
On Apr 30, 12:07 pm, dizzy <di...@roedu.net> wrote:
I wonder if this code is standard conformant and should work on all
conformant implementations (for some type T):
1: void* mem = ::operator new(sizeof(T));
2: T* p = new(mem) T(args...);
3: delete p;
line 2 I know it should be fine because global operator new
should return memory aligned for any type. The thing I wonder
about is line 3. Should this always work?
I think so, but I think the point is vague enough that I'd avoid
counting on it. The usual rule is to separate destruction and
deallocation anytime you've separated allocation and
initialization. In other words, you sould probably replace 3
with:
p->~T() ;
::operator delete( p ) ;
PS: the code might seem silly, it is needed because I need to
decouple the point of storage type used (which on 2 different
codepaths can be on stack or dynamic) from the point of actual
initialization of the object and its arguments (thus I need to
use placement new);
I'm not sure I understand this. If the object is on the stack,
it will have been constructed where it was declared, and will be
destructed when it goes out of scope. So you can't use
placement new on it later, and you can't explicitly delete it
in any way.
--
James Kanze (GABI Software) email:james.kanze@gmail.com
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