"Andy Little" <andy@servocomm.freeserve.co.uk> wrote in message
Does this mean it may (eventually) be possible to use template template params in BOOST_TYPEOF ?
Not yet :( What I am trying to achieve is much more modest: I want to extract template and a number of parameters from an unregistered type to achieve a more descriptive assertion. So that instead of : can't instantiate boost::typeof::encode_type<class std::map<class std::basic_string<char, struct std::char_traits<char>,class std::allocator<char> >,class std::basic_stri ng<char,struct std::char_traits<char>,class std::allocator<char> >,struct std::l ess<class std::basic_string<char,struct std::char_traits<char>,class std::alloca tor<char> > >,class std::allocator<struct std::pair<class std::basic_string<char ,struct std::char_traits<char>,class std::allocator<char> > const ,class std::ba sic_string<char,struct std::char_traits<char>,class std::allocator<char> > >
I could get something like this: MPL standard assertion text(boost::type_of::unknown_template_4<std::map>) Kind of exersize while reading the MPL book :) One problem that I have with mpl::template_arity, though, is that it seems to be undocumented... And therefore probably an internal feature? As for your question however, the conceptual problem with template template parameters is that they can't be returned from meta-functions: template<template<class> class T> class X { // I know T here, but how do I pass it outside??? }; Of course, they can be wrapped... I am wondering whether it would be possible to use this.... But again, not yet :) Regards, Arkadiy