具有对象成员回调的std函数

Question

I have a class that fires events, and I want to handle those event in another class. The following code shows what I am trying to achieve:

#include <functional>

using namespace std;

class StatusReport {
public:
    int value;
};

class Sender {
public:
    function<void(StatusReport *report)> ReportEvent;

    void test() {
        StatusReport *r = new StatusReport();
        ReportEvent(r);
    }
};


class Receiver {
public:
    Receiver() {
        Sender s = Sender();
        s.ReportEvent = std::bind(&Receiver::StatusReportEvent, this);
    }

    void StatusReportEvent(StatusReport *report) {
    }
};

int main() {
    Receiver r();
    return 0;
}

This generates an error when I try to bind the event to a method inside my receiver object. The error is

no match for call to ‘(std::_Bind<std::_Mem_fn<void (Receiver::*)(StatusReport*)>(Receiver*)>) (StatusReport*)’

What am I doing wrong here?

Answer 1

Since your function receives argument of type StatusReport bind should be called like

s.ReportEvent = std::bind
(
   &Receiver::StatusReportEvent, this, std::placeholders::_1
);

std::placeholders::_1 is a placeholder for argument.