Re: [Boost-users] Iterate over template arguments

On Wed, Nov 23, 2011 at 7:33 AM, Allan Nielsen wrote:

...

It might be me which does not understand it, but as I read the documentation funciton_types is for manipulating functions pointers, not to manage template arguments...

Please correct me if I'm wrong Okay, I got it... is one template argument... : typename boost::function_types::result_type<T0>::type is the return type, and I can use parameter_types and MPL to iterate over the parameters. Clever..

But how do I implement the call interface:

template<typename T > struct IfCall { typedef typename boost::function_types::result_type<T0>::type R;

R call( /* T0, T1, T2...*/ ) { // can I get the MPL sequence into the method signature?? } };

Ugh. Well, what I can think of at the moment: - Use the Boost.Preprocessor library to specialize each arity of lfCall, e.g., generate template< class R, class T0 > struct lfCall< R ( T0 ) > { /*...*/ R call(T0) { /*...*/ } }; and similarly for all other supported arities with the preprocessor; or - If you're flexible in the call interface, you might be able to utilize Boost.Fusion's fuse/unfuse adaptors [1]. - Jeff http://www.boost.org/doc/libs/1_48_0/libs/fusion/doc/html/fusion/functional/...