Re: [Boost-users] shared_ptr and global reset

Subject: Re: [Boost-users] shared_ptr and global reset
From: Wang Yun (a_hao_at_[hidden])
Date: 2009-02-25 09:38:25

Matthieu Guillo 写道:
> Hi Boosters
>
> Let's say that I have many shared_ptr<A> sharing ownership to the same 
> A object. At some point, I would like all those shared_ptr to point to 
> a  new  Object A. Is there an easy (and safe) way to accomplish that?
> I know how to do that for one shared_ptr using either "reset", either 
> operator =  but in order to do this for all shared_ptr sharing 
> ownership, the only way I could think of is through a registration 
> mechanism (like the Observer pattern) but this sounds an overkilling 
> process to me.
>
> So basically, is there a "global" reset method?
class A
{
public:
    explicit A(int v)
        : _v(v)
    {
    }

    int getV()
    {
        return _v;
    }

private:
    int _v;
};

    shared_ptr< scoped_ptr<A> > sp_a( new scoped_ptr<A> );
    (*sp_a).reset( new A(10) );

    shared_ptr< scoped_ptr<A> > sp_b( sp_a );
    shared_ptr< scoped_ptr<A> > sp_c( sp_a );

    sp_a->reset( new A(20) );

    assert( (*sp_b)->getV() == 20 );
    assert( (*sp_c)->getV() == 20 );