c++模块自动注册

https://github.com/qicosmos/Kapok

#pragma once

#include <map>
#include <string>
#include <functional>
#include <memory>
#include "Message.hpp"

struct factory
{
    template<typename T>
    struct register_t
    {
        register_t(const std::string& key)
        {
            factory::get().map_.emplace(key, &register_t<T>::create);
        }

        template<typename... Args>
        register_t(const std::string& key, Args... args)
        {
            factory::get().map_.emplace(key, [&] { return new T(args...); });
        }
        inline static Message* create() { return new T; }
    };

    inline Message* produce(const std::string& key)
    {
        if (map_.find(key) == map_.end())
            throw std::invalid_argument("the message key is not exist!");

        return map_[key]();
    }

    std::unique_ptr<Message> produce_unique(const std::string& key)
    {
        return std::unique_ptr<Message>(produce(key));
    }

    std::shared_ptr<Message> produce_shared(const std::string& key)
    {
        return std::shared_ptr<Message>(produce(key));
    }
    typedef Message*(*FunPtr)();

    inline static factory& get()
    {
        static factory instance;
        return instance;
    }
    
private:
    factory() {};
    factory(const factory&) = delete;
    factory(factory&&) = delete;
    
    std::map<std::string, FunPtr> map_;
};

//std::map<std::string, factory::FunPtr> factory::map_;

#define REGISTER_MESSAGE_VNAME(T) reg_msg_##T##_
#define REGISTER_MESSAGE(T, key, ...) static factory::register_t<T> REGISTER_MESSAGE_VNAME(T)(key, ##__VA_ARGS__);

/*
Message* p = factory::get().produce("message1");
p->foo();   //Message1
*/