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

From: Anders Dalvander (anders_at_[hidden])
Date: 2008-06-02 16:12:46

>
> 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.
>
Is your application threaded? If so couldn't you use thread_specific_ptr 
for emulating a instance-based functor?

class A;
class B;

class C
{
public:
   C()
   {
      instance().push_back(this);
   }

   ~C()
   {
      instance().pop_back();
   }

   int operator()(A* a, B* b)
   {
      // Do your stuff.
   }

   static int wrapper(A* a, B* b)
   {
      return instance().back()->operator()(a, b);
   }

private:
   C(const C& rhs);
   C& operator=(const C& rhs);

   static this_vector& instance()
   {
      this_vector* t = ptr.get();
      if (!t)
      {
         t = new this_vector();
         ptr.reset(t);
      }
      return *t;
   }

   typedef std::vector<C*> this_vector;
   static boost::thread_specific_ptr<this_vector> ptr;
};

typedef int (*foobar)(A*,B*);
void do_something(foobar cb);

C obj;
do_something(C::wrapper);

Regards,
Anders