How do I call a class by passing it's object and member function to another function in c++?

Question

How do I execute a member's function by passing the object and the member's function to another function in c++. I do understand the answer to my question is out there; however, I do not know what this is called. So far I created 2 files, exeFunc.h and exeFunc.cpp. Their code consist of:

exeFunc.h

/*
File: exeFunc.h

Header file for exeFunc Library.
*/

#ifndef EXEFUNC_H
#define EXEFUNC_H

#include "mbed.h"
#include "msExtensions.h"
#include "cfExtensions.h"

#include <map>

class exeFunc
{

public:
    exeFunc(msExtensions &msExt, cfExtensions &cfExt);

private:

    void _splitFuncFromCmd();
    void _attachCallback();

    msExtensions &_msExt;
    cfExtensions &_cfExt;

    //FunctionPointer _p;
};

#endif

exeFunc.cpp

/*
File: exeFunc.cpp

Execute functions in other Sensor libraries/classes

Constructor
*/

#include "mbed.h"
#include "ConfigFile.h"
#include "msExtensions.h"
#include "cfExtensions.h"
#include "exeFunc.h"

#include <map>
#include <string>

using namespace std;

exeFunc::exeFunc(msExtensions &msExt, cfExtensions &cfExt) : _msExt(msExt), _cfExt(cfExt)
{
    //_cfExt.checkConfigForFirstStart();
    //_p.attach(&_cfExt, &cfExtensions::checkConfigForFirstStart);

    //_p.call();

}

void exeFunc::_splitFuncFromCmd()
{

}

void exeFunc::_attachCallback()
{

}

Is this what you are looking for: http://stackoverflow.com/questions/130322/how-do-you-pass-a-member-function-pointer — jogojapan, Nov 28 '12 at 05:44
Do you want to pass the object, or a function pointer pointing to the member function? — SingerOfTheFall, Nov 28 '12 at 05:46
@SingerOfTheFall So far I have passed all my objects by Reference, but I have never created a function pointer pointing to the member function. Basically I am attempting to kill two birds with one stone by passing both the object and the member function so I can execute the function in a general fashion. — dottedquad, Nov 28 '12 at 05:54
@SingerOfTheFall Yes, I could do it that way. Is there a way that I can do that dynamically by passing the object and method to another function? — dottedquad, Nov 28 '12 at 05:57
@jogojapan That is what I am looking for; however, the template and all the other arguments in the class methods are clouding my understanding. — dottedquad, Nov 28 '12 at 06:35

score 2 · Accepted Answer · answered Nov 28 '12 at 05:57

2

I wrote a completed example, may helps

class MyClass
{
public:
    MyClass(int b)
        :_b(b)
    {
    }

    int Foo(int a)
    {
        return a * _b;
    }
    int _b;
};

typedef int (MyClass::*MFP)(int);

int get_result(MyClass* obj, MFP mfp)
{
    int r = (obj->*mfp)(5); // 30
    return r;
}

int _tmain(int argc, _TCHAR* argv[])
{
    MFP mfp = &MyClass::Foo;

    MyClass m(6);
    get_result(&m, mfp);


    return 0;
}

answered Nov 28 '12 at 05:57

Healer

290
1
7

1

Notice this line: int r = (obj->*mfp)(5); // 30 – Healer Nov 28 '12 at 05:57
The referenced objects _cfExt and _msExt have methods that I would like to execute upon request. – dottedquad Nov 28 '12 at 07:04

score 1 · Answer 2 · answered Nov 28 '12 at 05:53

1

You call it by another function.if you have an independent function.
To be honesty your question is not completely clear.However :

int F(int,int,int);
int g();
//main scope 
F(g(),a,b)

answered Nov 28 '12 at 05:53

bahrami703i

33
5

The best way that I can explain what I am attempting to do is, create a basic generic function pointer by passing the object and method to execute that function in a general way. – dottedquad Nov 28 '12 at 05:56
1

you should define a pointer to a function . what do you mean dynamically? – bahrami703i Nov 28 '12 at 06:09
By dynamically I mean pass the pointers to another function to execute the member's function. 'dynamically' was probably the wrong choice of word. – dottedquad Nov 28 '12 at 06:31

How do I call a class by passing it's object and member function to another function in c++?

2 Answers2