CompileTimeConstraints.hh

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#ifndef CompileTimeConstraints_hh
#define CompileTimeConstraints_hh

namespace CompileTimeConstraints
{
  template <class Base> char InheritsFrom(Base *);
  template <class Derived> Derived* DerivedPointer();
  template < class A, class B > struct IsA 
  { 
  public:
    enum { ok=(sizeof(InheritsFrom<B>(DerivedPointer<A>())) ) };
  };
}

#endif