c++怎么实现一个简单的信号槽机制_c++信号与槽机制的实现与应用

#include 
#include 
#include 

template 
class Signal {
private:
    using SlotType = std::function;
    std::vector slots_;
    int next_id_ = 0;
    std::vector free_ids_;

public:
    // 连接一个槽函数，返回连接ID
    int connect(SlotType slot) {
        int id;
        if (free_ids_.empty()) {
            id = next_id_++;
            slots_.push_back(slot);
        } else {
            id = free_ids_.back();
            free_ids_.pop_back();
            slots_[id] = slot;
        }
        return id;
    }

    // 断开连接
    void disconnect(int id) {
        if (id >= 0 && id < (int)slots_.size() && slots_[id]) {
            slots_[id] = nullptr;
            free_ids_.push_back(id);
        }
    }

    // 触发信号，调用所有有效槽
    void emit(Args... args) {
        for (const auto& slot : slots_) {
            if (slot) {
                slot(args...);
            }
        }
    }
};

#include 

struct Receiver {
    void onEvent(int value) {
        std::cout << "Received: " << value << "\n";
    }
};

void globalCallback(int value) {
    std::cout << "Global handler: " << value << "\n";
}

int main() {
    Signal sig;
    Receiver receiver;

    // 连接全局函数
    int conn1 = sig.connect(globalCallback);

    // 连接lambda
    int conn2 = sig.connect([](int v) {
        std::cout << "Lambda received: " << v << "\n";
    });

    // 连接成员函数（注意捕获receiver实例）
    int conn3 = sig.connect([&receiver](int v) {
        receiver.onEvent(v);
    });

    // 发送信号
    sig.emit(42);

    // 断开某个连接
    sig.disconnect(conn2);

    std::cout << "After disconnecting lambda:\n";
    sig.emit(100);

    return 0;
}