Is it possible to wrap boost sockets with Pimpl?

Question

in a project we want to wrap the Boost Asio socket in a way, that the using class or the wrapping .h does not have to include the boost headers.

We usually use pointers and forward declarations for wrapped classes.

Foward declaration:

namespace boost
{
  namespace asio
  {
    namespace ip
    {
      class udp;
    }
  }
}

And then declaring the socket:

  scoped_ptr<boost::asio::ip::udp::socket> socket_;
  scoped_ptr<boost::asio::ip::udp::endpoint> receiveEp_;

(If you don't know scoped_ptr, ignore it, the problem is equal with a standard * pointer.)

But this gives a compiler error:

error C2027: use of undefined type 'boost::asio::ip::udp'

I understand this is because udp is actually not a namespace, but a class itself. We only want to use the inner class though, any ideas?

Answer 1

With inner types your only option is wrapping everything. Hide scoped pointers themselves inside a forward declared class. Users would see only your API and pass around your own objects instead of boost objects.

In your example though scoped_ptr look like private member declarations, you can get away with simple:

// header
class SomeClass 
{ 
public:
    SomeClass();
    // stuff   
private: 
    scoped_ptr<class pimpl_bla> _m; 
};

// source
class pimpl_bla
{
public: 
    scoped_ptr<boost::asio::ip::udp::socket> socket_;
};

SomeClass::SomeClass() 
    :_m(new pimpl_bla)
{ 
}