从可变参数模板类中提取类型用于成员函数重载

Question

I would like to have a function overload for each type of a variadic template class. Is that possible ?

template<typename ...args>
class Example {
    virtual void doSomething(args(0) arg) { ... } 
    virtual void doSomething(args(1) arg) { ... }
    /// etc... implementations are the same, but I need access to the type
}

I tried using fold expressions but I'm pretty sure I'm not on the right track. Because I need the functions to be virtual, I cannot declare them as template<typename T> virtual void doSomething(T arg) because, well, template virtual functions aren't allowed.

Answer 1

You can derive the class from a templated pack of instantiations of a base class template that defines one virtual function with its single template parameter as the function parameter type. The derived class then holds the function overloads for each template argument type, that are all virtual.

template<typename arg>
class Base {
    virtual void doSomething(arg arg) {}
};

template<typename ...args>
class Example : public Base<args>... {};