Question

Hi I’ve got a static member of a templated class that I want defined for a sub group of classes that are templated ie:

template <typename T> 
class FooT
{
private:
 static int ms_id;
};

template <typename T> 
class Foo {};

template<> template<typename T> int FooT< template Foo<T> >::ms_id = 10;

Sadly this throws the following error under gcc 4.1.1

D:\X\Foo.h(98) : error: template argument 1 is invalid

on the line: template<> template<typename T> int FooT< template Foo<T> >::ms_id = 10;

What am I doing wrong is the general concept allowed in the first place?

Answer 1

You can do this by partially specializing an “initializer template”:

template <typename T> 
class FooT
{
private:
 static int ms_id;
};

template <typename T> 
class Foo {};

template <typename T>
class GetValue {
  static const int v = 0;
};

template <typename T>
class GetValue< Foo<T> > {
  static const int v = 10;
};

template<typename T> int FooT< T >::ms_id = GetValue<T>::v;