Create Generic Class with String?

    I create generic class. The type T is to be std::string or
std::wstring. I declare t variable to static const because I do not
want to modify string. C++ Compiler complies without errors.
    If you add std::cout to the main function body, then C++ Compiler
will fail to compile and the error message says

c:\my projects\colors\colors\main.cpp(1438) : error C2373: 't' :
redefinition; different type modifiers
        c:\my projects\colors\colors\main.cpp(1434) : see declaration
of 't'
        c:\my projects\colors\colors\main.cpp(1438) : while compiling
class template static data member 'const std::string Foo<T>::t'
        with
        [
            T=std::string
        ]
        c:\my projects\colors\colors\main.cpp(1444) : see reference to
class template instantiation 'Foo<T>' being compiled
        with
        [
            T=std::string
        ]

template< typename T >
class Foo
{
public:
    Foo<T>() {}
    ~Foo<T>() {}

    static const T t;
};

template< typename T >
T Foo<T>::t = "Hello World!\n";

int main()
{
    Foo<std::string> f;
    std::cout << f.t;

    return 0;
}

    What happen if I declare std::wstring instead of std::string? C++
Compiler will fail to compile because =91L' is not added before string
=94Hello World!\n=94.
    I do not want to create two separate classes. One is for string and
another one is for wstring. I add preprocessor condition.

#if !defined( UNICODE )
    template< typename T >
    std::string Foo<T>::Text = "Hello World!\n";
#else
    template< typename T >
    std::wstring Foo<T>::wText = L"Hello World!\n";
#endif

    Do you have the solution?