Vyacheslav Kononenko writes:

Hi,

I've been trying boost::mpl for my current project and hit a problem. Sorry if it is an already known issue. So if we have our own metafucntion: template< typename T, typename Value > func : mpl::void_ {};

it works fine: typedef mpl::find_if< mpl::vector< int, char >, func< mpl::_1, mpl::int_< 10 > >::type iter; ...

But if I try to use integral value instead: template< typename T, int Value > func : mpl::void_ {};

and

typedef mpl::find_if< mpl::vector< int, char >, func< mpl::_1, 10

...

::type iter;

It fails on gcc 3.3.3 nor 3.4.3.

No surprise. This func doesn't fit the Metafunction concept: http://www.boost.org/libs/mpl/doc/refmanual/metafunction.html A metafunction is a class or a class template that represents a function invocable at compile-time. An non-nullary metafunction is invoked by instantiating the class template with particular template parameters (metafunction arguments); the result of the metafunction application is accessible through the instantiation's nested type typedef. All metafunction's arguments must be types (i.e. only type ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ template parameters are allowed). A metafunction can have a variable ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ number of parameters. A nullary metafunction is represented as a (template) class with a nested type typename member. HTH, -- Dave Abrahams Boost Consulting www.boost-consulting.com