Re: Rebirthing an object... just making sure

From:
"Tom1s # hilidhe" <toe@lavabit.com>
Newsgroups:
comp.lang.c++
Date:
Thu, 10 Jan 2008 16:57:19 GMT
Message-ID:
<Xns9A21AC799ECC5toelavabitcom@194.125.133.14>
"Tom1s # hilidhe" <toe@lavabit.com> wrote in comp.lang.c++:

And of course, if the constructor of T throws, you still leak
the memory. You really need something like:

    template< typename T >
    void
    renewObject( T*& obj )
    {
        // Fail if object has a derived type...
        assert( typeid( *obj ) == typeid( T ) ) ;
        obj->~T() ;
        try {
            new( obj ) T ;
        } catch ( ... ) {
            ::operator delete( obj ) ;
            obj = NULL ;
            throw ;
        }
    }


I'm intending for there to be a leak, because the dialog's class code
deletes its controls automatically when the dialog is closed.


Wups a daisy... about five seconds after I posted that I realised I'd
need a catch to set the pointer to null to avoid the dialog's class from
calling the destructor on an object that's already been destructed.

Anyway, in my own particular program, it's a fatal error if you can't
rebirth an object, so I think I'll go with:

template<class T>
void Rebirth(T &obj)
{
    obj.~T();

    try { ::new(&obj) T(); } catch (...) { exit(EXIT_FAILURE); };
}

--
Tom1s # hilidhe

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