c++ - 使用函数指针在类之间传递数据

Question

我试图通过传递一个函数指针来使类似的东西工作。我知道你可以将第一个类的指针传递给第二个，然后让第二个通过指针触发第一个类的成员函数。但我不想让二等类依赖于知道一等类是谁。这更像是我正在寻找实现这一目标的编码风格。谢谢

//////////////////////////////////////////////////
class Second
{
public:
    Second::Second(void (*SecondTriggered)(void));
};

Second::Second(void (*SecondTriggered)(void))
{
    SecondTriggered();
}


//////////////////////////////////////////////////
class First
{
public: 
    First::First();
    void SecondTriggered();
    Second *second;
};

First::First(){
        printf("first class was created"); 
    second = new Second(SecondTriggered);
}

void First::SecondTriggered(){
    printf("second class was created and responded"); 
}

/////////////////
int main()
{
    First *first = new First();
 } 

我收到这个错误:

error C3867: 'First::SecondTriggered': function call missing argument list; 
use '&First::SecondTriggered' to create a pointer to member

任何想法。

Answer 1

您正试图在需要独立函数的地方传递一个非静态类成员。要执行您正在尝试的操作，您必须改为执行以下操作:

class Second
{
public:
    Second::Second(void (*SecondTriggered)(void*), void *arg);
};

Second::Second(void (*SecondTriggered)(void*), void *arg)
{
    SecondTriggered(arg);
}


//////////////////////////////////////////////////
class First
{
public: 
    First::First();
    static void SecondTriggered(void *arg);
    Second *second;
    void DoSomething();
};

First::First(){
    printf("first class was created"); 
    second = new Second(&SecondTriggered, this);
}

void First::SecondTriggered(void *arg){
    printf("second class was created and responded"); 
    static_cast<First*>(arg)->DoSomething();
}

void First::DoSomething(){
    printf("first class did something");
}

/////////////////
int main()
{
    First *first = new First();
 }