Re: [boost] [Smart Ptr][Bind] Implementaion of Weak Callback Function

Subject: Re: [boost] [Smart Ptr][Bind] Implementaion of Weak Callback Function
From: Artyom (artyomtnk_at_[hidden])
Date: 2009-03-22 01:41:11

>   foo = bind( &bar::slot, bind(
> &weak_ptr<bar>::lock, weak_ptr<bar>(
> bar_ptr ) ) );
> 

Such solution may work if you would write

void bar::slot()
{
  if(!this) return;
// or
  if(!this) throw something();
}

But I this is just a hack.

More then that, throwing is not good idea because generally
I do not want this situation be treated as a error.

> However, one of those binds must be persisting the smart
> pointer
> somewhere, because calling foo always has an effect for me,
> where I
> would expect it to segfault after the shared_ptr is reset,
> since
> lock() would return a null shared_ptr. You might be able to
> see the
> problem though, and get where you want to be.

Such "second" bind should return a "void" function that does
nothing, that what I solve in weak_fn.

Actually the code of weak_fn is quite simple (when using variadic
templates, otherwise it is just many copies of same code for 0, 1 
and N parameters).

Suggestions? Comments?

Artyom

> 
> HTH,
> Christopher
> _______________________________________________
> Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost