CODEWITHSUNDEEP
c++inheritance
eightlay
eightlay

Reputation: 542

Inheritance with template classes

I'm trying to figure out, how can I inherit from template class to template class. The problem is: I can't use protected members of Parent class.

Example:

template <class N>
class Parent {
protected:
    N member;
public:
    Parent(N aa){
        member = aa;
    }
};


class Child1: public Parent<int>{
    public:
        Child1(int a): Parent<int>(a) {
            member += 1; // works
        }
};

template<class Q>
class Child2: public Parent<Q>{
    public:
        Child2(int a): Parent<Q>(a) {
            member += 1; // does not work (use of undeclared identifier)
        }
};

How can I use "member" in the Child2 class?

Thanks for your time

Upvotes: 4

Views: 1743

Answers (1)

Patrick Roberts
Patrick Roberts

Reputation: 51826

You need to use this->member or Parent<Q>::member.

In the second case, member is a "dependent name" because the existence of member from the base class template Parent<Q> depends on the type of class Q in the template, whereas in the first example there is no dependent type, the compiler can statically analyze that Parent<int> contains member.

Upvotes: 4

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