template <class T >
   class MyClass {
     private:
       T value;
     public:
        MyClass(T value_ = T()):value(value_){cout<<"from Constructor value = "<<value<<endl;}
        
       template <class X>
       void assign(const MyClass<X>& x) { // x must have same type as *this
           value = x.value;
       }

        T getValue()const
        {
            return value;
        }
   };

int main( int argc, char ** argv )
{
    MyClass<int> T1, T3;
    MyClass<double> T2;


    T1.assign(T3); //нет ошибки 
    T1.assign(T2); //error C2248: 'MyClass<T>::value' : cannot access private member declared in class 'MyClass<T>'

  return 0;
}