Re: [Boost-users] [enable_if] Type choices

Hi! Using mpl in your case is not a lot of work ;) Just use the mpl::set for the set of accepted types and the mpl::has_key meta-function in conjunction with enable_if. //////////// UNTESTED CODE //////////////////// #include #include #include .... typedef set< char,wchar_t> accepted_types; template<class T> void foo( T t , typename boost::enable_if < typename boost::mpl::has_key::type >::type* reserved=0 ) { ... } /////////////// END OF UNTESTED CODE //////////////// Good Luck, Ovanes On 3/24/08, Robert Dailey wrote:

Hi,

I have a simple template function that takes one argument. For example:

template< typename t_type > void foo( t_type param ) { }

I want to restrict the type of t_type to a certain subset of types, such as 'char' or 'wchar_t'. If the user passes in any type other than those two types, the compiler should not be able to find an overload for foo() that matches the argument types. Note that I would also be using boost::enable_if to test this condition, however I do not see anything in type_traits or anywhere else to perform such a test.

I thought of using mpl::vector to create a list of types the function would take and using enable_if to check if the type is in the container, but this seems like a lot of work. I want to see if there is a simpler, more compact solution.

Thanks.

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