Re: [Boost-users] boost & c-style calback issue

From: Michael Bradley Jr (mbradley.jr_at_[hidden])
Date: 2008-06-02 11:11:23

Hi,

Nikolai N Fetissov wrote:
>> Making the member function that has that signature static helps solve the
>> problem but then we do have undesirable side-effect since this operation
>> should
>> be instance based and not object-bases.
>> May be someone can come out with a better approach?!
>
> With such restriction I would go with making C a singleton
> (or pooled object - same idea) and doing something like:
>
>    class C {
>    public:
>      int DoStuff( A*, B* ); // or op() - doesn't matter
>      static C&  GetInstance( /*XXX*/ ); // or pointer
>    private:
>      // singleton stuff ...
>    };
>
>    // extern "C" ?
>    int CallbackFunc( A* a, B* b ) {
>      return C::GetInstance( /*XXX*/ ).DoStuff( a, b );
>    }
>
>    do_something( CallbackFunc );
>
> This is of course just one way of doing things and very
> much depends on the context. Generally, you got a
> subsystem boundary and need to figure out a clean interface.
>

Your approach is exactly what we don't want, since it makes it an object-based 
based solution rather than instance-based.
We are using a functor (therefor the oprerator()) so that the solution remains 
instance-based.

Like I've said we want to apply it to different instances of C with their own 
different and non-static member variables.

C c1,c2,c3;

Did google a bit and one possible solution was boost::function in combination 
with boost::bind. But I'm not familiar to that ;(

Cheers
Mike