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c++templatesinheritancealias
Omegaman
Omegaman

Reputation: 2329

inheritance of type aliases within templates

It looks like I an inherit type aliases among classes, but not among class templates? I don't understand why this code works:

#include <iostream>

//template<typename T>
struct Test1
{
//    using t1=T;
    using t1=int;
};

//template<typename T>
struct Test2: public Test1//<T>
{
  t1 x;  
};

int main(int argc, char *argv[]) {
//    Test2<int> a;
    Test2 a;
    a.x=5;
    std::cout << a.x << std::endl;
}

and this code does not:

#include <iostream>

template<typename T>
struct Test1
{
    using t1=T;
};

template<typename T>
struct Test2: public Test1<T>
{
  t1 x;  
};

int main(int argc, char *argv[]) {
    Test2<int> a;
    a.x=5;
    std::cout << a.x << std::endl;
}

Do types not inherit through templates?

Upvotes: 9

Views: 4184

Answers (1)

sgun
sgun

Reputation: 899

The following will work:

 typename Test1<T>::t1 x;

and, as Xeo points out in the comments above, so does:

typename Test2::t1 x;

Upvotes: 4

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