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May 9th, 2009

assign number to function

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Hi and sorry for the inconvenience

I am trying to make an interface where a function is run given a number(windows API).

I want a default function to be run if it hasn't been overwritten by the user.

So my question is can i assign a number to a function/method
like using this number I am going to access this function.

Any help is deeply appreciated

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May 9th, 2009

Re: assign number to function

something like this:

C++ Syntax (Toggle Plain Text)
void foo( int x = 0)
{
   switch( x )
   {
       case 0:
           printf("case 0\n");
           break;
         case 1:
           printf("case 1\n");
           break;
        default:
           printf("default\n");
           break;
    }
}
 
int main()
{
    foo();
    foo(1);
}
void foo( int x = 0)
{
   switch( x )
   {
       case 0:
           printf("case 0\n");
           break;
         case 1:
           printf("case 1\n");
           break;
        default:
           printf("default\n");
           break;
    }
}

int main()
{
    foo();
    foo(1);
}

Last edited by Ancient Dragon; May 9th, 2009 at 1:17 pm.

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May 9th, 2009

Re: assign number to function

Yes but in an automated way so I can add functions at runtime and make it have a value.

I know I could do this with a loop and an if statement but it would be optimal if could check if the message is being handled and abort if not

btw should I use function pointers for this?

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Re: assign number to function

Yes, function pointers might be helpful, but you would still have to have a list of pre-defined functions just as I had in the code I posted. For example if the command string were "say hello" the program could not call a function say() at run time unless it was already known at compile time.

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Re: assign number to function

The problem is that it is the windows API we are talking about and I can't have a predefined function for every windows message.

I was thinking something like obtaining a function pointer and the message number from the user and let that overwrite the default behavior(DefWindowProc()).

so I was thinking maybe there was a way of connecting the function and the number

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Re: assign number to function

If the program knows the HWND handle then call SetWindowLong() to hook into its default proc

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Re: assign number to function

Thank You!

this is what I've got.
There are some problems and you can't replace a function but I can handle that myself

CPP Syntax (Toggle Plain Text)
class msghandler
{
public:
    void HandleMessage(WNDPROC func, UINT msg);
    LRESULT CALLBACK handle(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
private:
    std::vector<msg_func> msglist;
};
 
LRESULT msghandler::handle(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    std::vector<msg_func>::iterator iter;
 
    for(iter = msglist.begin(); iter < msglist.end(); iter++)  //loop until find match
    {
        if((*iter).msg == msg)
        {
            return (*iter).function(hWnd, msg, wParam, lParam); //return user defined function's return value
        }
    }
    return DefWindowProc(hWnd, msg, wParam, lParam);  //return DefWindowProc
}
 
void msghandler::HandleMessage(WNDPROC func, UINT msg)
{
    msg_func temp;
 
    temp.function = func;
    temp.msg = msg;
 
    msglist.push_back(temp);
}
class msghandler
{
public:
    void HandleMessage(WNDPROC func, UINT msg);
    LRESULT CALLBACK handle(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
private:
    std::vector<msg_func> msglist;
};

LRESULT msghandler::handle(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    std::vector<msg_func>::iterator iter;

    for(iter = msglist.begin(); iter < msglist.end(); iter++)  //loop until find match
    {
        if((*iter).msg == msg)
        {
            return (*iter).function(hWnd, msg, wParam, lParam); //return user defined function's return value
        }
    }
    return DefWindowProc(hWnd, msg, wParam, lParam);  //return DefWindowProc
}

void msghandler::HandleMessage(WNDPROC func, UINT msg)
{
    msg_func temp;

    temp.function = func;
    temp.msg = msg;

    msglist.push_back(temp);
}

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