Question

I would to make a template match only for T=std::vector<T2> arguments (T2 is an arbitrary type). I can use boost::enable_if in template arguments. How do I test whether a type T is a std::vector?

I could include T::iterator in my template so that non-container types would lead to substitution failure and would not be considered (SFINAE). This way though, any containers which define T::iterator would match, not only std::vector<T2>.

Answer 1

You probably don’t need enable_if, a simple partial specialization should be enough:

template <typename T>
struct Type { ... };

// partial specialization for std::vector
template <typename T>
struct Type< std::vector< T > > { ... };

If you are dealing with a function template, you can simply provide an overload:

template <typename T>
void foo( const T & t ) { ... }

// overload for std::vector
template <typename T>
void foo( const std::vector< T > & vec ) { ... }