From: Jeff Mirwaisi (jeff_mirwaisi_at_[hidden])
Date: 2005-02-23 09:00:57
documentation, but just for completeness.
Given a type trait TT which you want to select upon.
Given a template function TF which you would like to
call only for types that TT selects from within
template function G.
We need a type which will delegate to TF, that doesn't
bind the template parameter types and is a first class
type (a holder)
template <typename T> void TF(T) {}
struct TF_holder
{
typedef void result_type;
template <typename T> result_type invoke(T t)
{return TF(t);}
};
template <typename U> void G(U u) { execute_if< TT< U
>::invoke< TF_holder >(u); }
G is the generic template function for all types, TF
is the conditionally targeted template function for
types for which TT is true.
Hope that helps.
Jeff Mirwaisi