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c++ - 在地图中存储通用回调

问题描述

我想创建一个 id / 通用回调映射，但我不知道它是否可行。我的想法是这样的：不同的国王od对象

class Class1
{
public:
    bool run(const int &temp){
        std::cout << "worker1:" << temp << std::endl;
        return 0;
    }
};
class Class2
{
public:
    bool run(const std::string &temp){
        std::cout << "worker2:" << temp << std::endl;
        return 0;
    }
};

回调对象的模板：

template <typename ReturnType, typename... Args>
class Callback
{
private:
    std::function<ReturnType> _function;

public:
    Callback(std::function < ReturnType(Args...)> function) 
        : _function(function){}

    auto run(Args... args)
    {
        return function(std::forward<Args>(args)...);
    }
};

使用示例

int main() {
    Class1 class1;
    Class2 class2;

    std::map<int, Callback> cbs;

    cbs[1] = std::bind(&Class1::run, &class1, std::placeholders::_1));
    cbs[2] = std::bind(&Class1::run, &class1, std::placeholders::_1));

     cbs[1].run(1);
     cbs[2].run("string msg");           
}

标签： c++c++11c++14c++17

解决方案

也许你可以用std::any

我创建了工厂，在其中存储了带有地图中任何签名的函数。

请看一下，如果它可以给你一个想法。否则我会删除这个答案

#include <iostream>
#include <map>
#include <utility>
#include <any>


// Some demo classes ----------------------------------------------------------------------------------
struct Base {
    Base(int d) : data(d) {};
    virtual ~Base() { std::cout << "Destructor Base\n"; }
    virtual void print() { std::cout << "Print Base\n"; }
    int data{};
};
struct Child1 : public Base {
    Child1(int d, std::string s) : Base(d) { std::cout << "Constructor Child1 " << d << " " << s << "\n"; }
    virtual ~Child1() { std::cout << "Destructor Child1\n"; }
    virtual void print() { std::cout << "Print Child1: " << data << "\n"; }
};
struct Child2 : public Base {
    Child2(int d, char c, long l) : Base(d) { std::cout << "Constructor Child2 " << d << " " << c << " " << l << "\n"; }
    virtual ~Child2() { std::cout << "Destructor Child2\n"; }
    virtual void print() { std::cout << "Print Child2: " << data << "\n"; }
};
struct Child3 : public Base {
    Child3(int d, long l, char c, std::string s) : Base(d) { std::cout << "Constructor Child3 " << d << " " << l << " " << c << " " << s << "\n"; }
    virtual ~Child3() { std::cout << "Destructor Child3\n"; }
    virtual void print() { std::cout << "Print Child3: " << data << "\n"; }
};



using UPTRB = std::unique_ptr<Base>;


template <class Child, typename ...Args>
UPTRB createClass(Args...args) { return std::make_unique<Child>(args...); }

// The Factory ----------------------------------------------------------------------------------------
template <class Key, class Object>
class Factory
{
    std::map<Key, std::any> selector;
public:
    Factory() : selector() {}
    Factory(std::initializer_list<std::pair<const Key, std::any>> il) : selector(il) {}

    template<typename Function>
    void add(Key key, Function&& someFunction) { selector[key] = std::any(someFunction); };

    template <typename ... Args>
    Object create(Key key, Args ... args) {
        if (selector.find(key) != selector.end()) {
            return std::any_cast<std::add_pointer_t<Object(Args ...)>>(selector[key])(args...);
        }
        else return nullptr;
    }
};

int main()
{
    Factory<int, UPTRB> factory{
        {1, createClass<Child1, int, std::string>},
        {2, createClass<Child2, int, char, long>}
    };
    factory.add(3, createClass<Child3, int, long, char, std::string>);


    // Some test values
    std::string s1(" Hello1 "); std::string s3(" Hello3 ");
    int i = 1;  const int ci = 1;   int& ri = i;    const int& cri = i;   int&& rri = 1;

    UPTRB b1 = factory.create(1, 1, s1);
    UPTRB b2 = factory.create(2, 2, '2', 2L);
    UPTRB b3 = factory.create(3, 3, 3L, '3', s3);

    b1->print();
    b2->print();
    b3->print();
    b1 = factory.create(2, 4, '4', 4L);
    b1->print();
    return 0;
}

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