I'm writing a function template like this:
template <class T>
class MyClass() {}
template <typename A, typename B>
auto func(A<B>& data) {
return MyClass<B>();
}
So I can using the function like this:
vector<int> vi; auto a = func(vi);
vector<string> vs; auto b = func(vs);
list<int> li; auto c = func(li);
list<string> ls; auto d = func(ls);
But obviously it's not allowed. How should I write a template to reach my goal?
You can declare A as template template parameter, otherwise you can't use it as A<B> in the function parameter declaration since it's not considered as template.
template <template <typename...> class A, typename B>
auto func(A<B>& data) {
// ... use B as the data type ...
}
Another way is STL containers (including std::vector and std::list) have a member type as value_type, you can use it as
template <typename A>
auto func(A& data) {
using B = typename A::value_type;
// ... use B as the data type ...
}
This should work:
template <class T>
class MyClass {};
template <template <typename, typename...> typename A, typename B, typename ... REST>
auto func(A<B,REST...>& data) {
return MyClass<B>();
}