Re: Template typedefs

As we know, using template typedefs is illegal in C++:

template <typename T>
typedef std::vector<T> Vector; // won't compile

It is suggested, that the following workaround can be used to
implement "template typedefs":

template <typename T>
struct Types
{
     typedef std::vector<T> Vector;

};

...

Types<int>::Vector numbers;

However, this prevents some argument deduction scenarios when calling
a templated function. The following example compiles on MSVC 9.0:

//----------------------------------------------------------

#include <vector>

template <typename T>
void signify( const std::vector<T>& )
{

}

int main()
{
        std::vector<int> v;
        signify( v );
        return 0;

}

//----------------------------------------------------------

Whereas the following doesn't:

//----------------------------------------------------------

#include <vector>

template <typename T>
struct Types
{
        typedef std::vector< T > Vector;

};

template <typename T>
void signify( const typename Types< T > :: Vector& )
{

}

int main()
{
        Types< int > :: Vector v;
        signify( v );
        return 0;

}

//----------------------------------------------------------

The error concerns "signify( v );" line and is reported to be : "
could not deduce template argument for 'T' "

Is there a workaround to make argument deduction function with
templated typedefs?