Inheritance and templates in C++ - why are inherited members invisible?

Question

When a template publicly inherits from another template, aren't the base public methods supposed to be accessible?

template <int a> class Test { public:     Test() {}     int MyMethod1() { return a; } };  template <int b> class Another : public Test<b> { public:     Another() {}     void MyMethod2() {         MyMethod1();     } };  int main() {     Another<5> a;     a.MyMethod1();     a.MyMethod2(); } 

Well, GCC craps out on this... I must be missing something totally obvious (brain melt). Help?

Answer 1

This is part of the rules concerning dependent names. Method1 is not a dependent name in the scope of Method2. So the compiler doesn't look it up in dependent base classes.

There two ways to fix that: Using this or specifying the base type. More details on this very recent post or at the C++ FAQ. Also notice that you missed the public keyword and a semi-colon. Here's a fixed version of your code.

 template <int a> class Test { public:     Test() {}     int MyMethod1() { return a; } };  template <int b> class Another : public Test<b> { public:     Another() {}     void MyMethod2() {         Test<b>::MyMethod1();     } };  int main() {     Another<5> a;     a.MyMethod1();     a.MyMethod2(); }