MFC Delagates

Introduction

The arrival of .NET brought some very nice approaches and techniques. Of course, one main reason of .NET code efficiency (I mean from a developer's scope) is that .NET languages are fully and exclusively object oriented.

One very nice attribute of .NET (and especially of C#) is delegates. Delegates are defined as member variables, and can hold references to functions.

Can C++ (and I meal real (native) C++) simulate this approach? While I am developing a very nice project in MFC, I realized that I can do (or even simulate) everything (with C++) that all other languages do. The only thing that I have noticed C++ does not have are function definitions in functions, as Delphi and Pascal have.

Anyway, because I wanted to get rid of non object oriented event handlings that MFC have (DECLARE MAPS... etc.), I tried to develop a template class that simulates C# delegates. And it wasn't so difficult.

The Class

The class is as follows:

//

// 

template <class FP, class SENDER,

class ARG1=int, class ARG2=int, class ARG3=int, class ARG4=int,

class ARG5=int, class ARG6=int, class ARG7=int, class ARG8=int>

class GDDelegateS

{

public:

    struct FPDATA

    {

        FP fp; //function pointer

        void *data;

    };

public:

    GDDelegateS()

    {

        m_List = NULL;

        m_ListCount = 0; 

    }

    virtual ~GDDelegateS()

    {

        Clear();

    }

protected:

    FPDATA *m_List;

    int m_ListCount;

public:

    void Add(FP funct, void *data)

    {

        FPDATA *nList = new FPDATA[m_ListCount+1];

        FPDATA *f=NULL;

        for(int i=0;i<m_ListCount;i++)

        {

            if(funct==m_List[i].fp && data == m_List[i].data)

            {

                delete []nList;

                return;

            }

            nList[i].data = m_List[i].data;

            nList[i].fp = m_List[i].fp;

        }

        nList[i].data = data;

        nList[i].fp = funct;

        if(m_List)

        delete m_List;

        m_List = nList;

        m_ListCount++;

    }

Read more: Codeproject

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