Deducing Template Arguments for Member Functions and Variables

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Apologies for the confusing title, I couldn't find a clearer way to express my question. I'm trying to use std::functions for implementing callbacks. The idea is to map "actions" to functions and provide an easy interface to keep track of which functions to call when a certain action happens.

Here's a simplified version of my class:

template<typename ID, typename Return, typename ...Args>
class A
{
public:
    void Register(ID id, std::function<Return(Args...)> funct)
    {
        m_listeners.emplace(id, funct);
    }
    A() {}
    ~A() {}
private:
    std::unordered_multimap<ID, std::function<Return(Args...)> > m_listeners;

};

What I really want is A to have only 1 template template so when A is declared underlying container can still accept function with any return type and any number of arguments.

I don't have much experience with templates I'm not even sure what I'm trying to do is possible, but I need to hide the template parameters for unordered_multimap from class A.

What I'm trying to do would look something like this:

template<typename ID>
class A
{
public:
    template<typename Return, typename ...Args>
    void Register(ID id, std::function<Return(Args...)> funct)
    {
        m_listeners.emplace(id, funct);
    }
    A() {}
    ~A() {}
private:
    template<typename Return, typename ...Args>
    std::unordered_multimap<ID, std::function<Return(Args...)> > m_listeners;
};

Is there any way to achieve this?

asked 1 min ago

user1880907

63

Deducing Template Arguments for Member Functions and Variables