[Boost-users] [boost-users][mpl, enable_if] checking if a type has specific dependant type

Subject: [Boost-users] [boost-users][mpl, enable_if] checking if a type has specific dependant type
From: Igor R (boost.lists_at_[hidden])
Date: 2008-12-31 07:09:54

Hello,

I'd like to define a trait that would evaluate to true for types that
have some specific dependant type (DependentType), to use like this:
template<class Type> func(int i, typename
boost::enable_if<HasDependentType<Type> >::type* dummy = 0)
{
}

I tried this way:

template<class Type, class Enable = void> struct HasDependentType :
mpl::false_ {};
template<class Type> struct HasDependentType<Type, typename
Type::DependentType> : mpl::true_ {};

...but it appears incorrect (partial specialization is never ised).

Thanks in advance.