#include
<boost/preprocessor/repetition/enum_params.hpp>
#ifndef
TYPELIST_MAX_SIZE
# define
TYPELIST_MAX_SIZE 7
#endif
template
<BOOST_PP_ENUM_PARAMS(TYPELIST_MAX_SIZE, class T)>
class ObjectImpl :
BOOST_PP_ENUM_PARAMS(TYPELIST_MAX_SIZE, public T), public
ObjectBase<REFCNTR>
{
public:
virtual
Refcount acquire() const
{
return Base::acquire();
}
virtual
Refcount release() const
{
return Base::release();
}
virtual
Refcount getRefcount() const
{
return Base::getRefcount();
}
virtual bool
hasInterface(InterfaceID const & iid) const
{
return Base::hasInterface(iid);
}
virtual IObject
* getInterface(InterfaceID const & iid)
{
IObject const * const_this = (IObject const *)
this;
return (IObject *)
const_this->getInterface(iid);
}
virtual IObject
const * getInterface(InterfaceID const & iid)
{
IObject const * obj = 0;
switch (iid)
{
case IObject::IID :
{
this->acquire();
obj = static_cast<IObject const *>(this);
break;
}
// Desired: for each type T in typelist generate the following case
block
// case T::IID :
// {
// this->acquire();
// obj = static_cast<T const
*>(this);
// break;
// }
default :
{
throw InterfaceUnsupportedException(iid)
break
}
}
return obj;
}
protected:
ObjectImpl()
{
}
virtual
~ObjectImpl()
{
}
typedef
ObjectBase<REFCNTR> Base;
};
What is the best way to generate a
case block for each type in the typelist? I’ve been looking at the
Preprocessor appendix from the “C++ Template Metaprogramming” book (can’t
wait!) and see three different approaches to vertical repetition: local, file
and self; however, I’m not clean on how to express what I want using these
approaches. Can someone shed some light, or point me to an example in
the Boost PP docs which solves a similar problem?
Many thanks in
advance…
-allen