On Wed, Feb 25, 2004 at 09:18:08PM -0600, Max Motovilov wrote:
(well, obviously....). FWIW, here's what the "universal operator+" becomes then:
template< typename T1, typename T2, template< typename _ > class DAT > inline typename boost::disable_if_c< do_not< promote_sum< DAT > >::value, DAT< typename boost::result_of_plus<T1,T2>::type >
::type operator+( const DAT<T1>& a, const DAT<T2>& b ) { typedef DAT< typename boost::result_of_plus<T1,T2>::type > T; return T( a ) + T( b ); }
Is there a way to avoid template<... template< typename _ > class DAT > ? While I don't know a class like this offhand, I can imagine a class that's typically instantiated along the lines of SomeClass<Foo,float> SomeClass<Foo,double> SomeClass<Bar,float> SomeClass<Bar,double> and it would be swell if the "DAT" technique generalized so that you could specify that you wanted to DAT-ify SomeClass<Foo,_1> I haven't thought about it hard enough, but it seems like something along the lines of changing it to template <class X, class Y> // enable_if both X and Y "isa" DAT (of the same kind) // based on specialization of result_xxx traits, deduce what was // called T1/T2 before operator+( const X& x, const Y& y ) { ... } My hunch is that it's possible, but I'm not totally sure. -- -Brian McNamara (lorgon@cc.gatech.edu)