Re: [boost] [smart_ptr] shared_ptr<T> T destructor requiredevenifadeleter function is provided

29 Sep 2008

      ----- Original Message ----- 
From: "Peter Dimov" <pdimov@pdimov.com>
To: <boost@lists.boost.org>
Sent: Monday, September 29, 2008 12:44 PM
Subject: Re: [boost] [smart_ptr] shared_ptr<T> T destructor 
requiredevenifadeleter function is provided
...
vicente.botet:
...
Hello Peter,
what about the following in which we don't transfer ownership. (Note that 
now X::create() return X*)
int main () {
   shared_ptr<X> ptr(X::create(), X::deleter());
   ptr.reset(X::create());
This is the equivalent of doing
shared_ptr<X> ptr( X::create() );
which you're explicitly trying to prevent. The equivalent of
...
shared_ptr<X> ptr(X::create(), X::deleter());
is
ptr.reset( X::create(), X::deleter() );
...
return 0;
}
Peter ,

thanks for pointing me to
template<class Y, class D> void reset(Y * p, D d);

I was not aware that deleter is associated to the pointer instance and not 
to the shared_ptr. I see now.

I suppose that you have already discused about a template version of 
shared_ptr and that you have good raisons no not include them for the 
standard. Please could you point me to the rational?

Has a wrapper class that takes the deleter and allocators as template 
parameter has a sence?

template <typename T, typename Deleter, typename Allocator>
struct shared_ptr_wrapper : private shared_ptr<T>
{
    ...
    void reset(T * p) {
        this->shared_ptr::reset(p, Deleter())
    }
    ...
}

Sorry for the noice and thanks again,

Vicente