Re: [Boost-users] [operators] boost::operators-like functionality for methods

From: François Duranleau (duranlef_at_[hidden])
Date: 2005-10-13 10:44:13

On Wed, 5 Oct 2005, Geoffrey Irving wrote:

> Hello,
>
> Is it possible to get boost::operator like functionality for general methods?
> In other words, I'd like to be able to do the following:
>
> template<...> struct complete : public ...
> {
>    void f(){a();}
>    void g();
> };
>
> struct C : public complete<...>
> {
>    void a();
>    void b(){g();}
> };
>
> The resulting class C would have methods a,b,g,f.  Here C::b refers to
> the complete::g and complete::f refers to C::a, so the dependencies are
> circular.  It seems like the boost::operators setup can handle this kind
> of circular dependency, but I'm not how to do it for methods.

I am doing that for implementing some vector operations (I mean, math 
vectors), e.g. normalization, negation, swap, etc. I need this circular 
dependency to access the bracket operator. But you can do the same for 
anything else. In your case, you could do something like:

struct empty_base {} ;

template < typename Derived ,
            class Base = empty_base >
struct complete
     : Base // if you want to chain operations as in Boost.Operators
{
     void f()
     {
         static_cast< Derived* >( this )->a() ;
     }

     void g() { /*...*/ }

} ;

struct C
     : complete< C >
{
   private :

     typedef complete< C > base_type_ ;

   public :

     void a() { /*...*/ }

     void b()
     {
         base_type_::g() ;
     }

} ;

--
Francois