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pointer to member-function

Started by merwin May 11, 2004 at 4:59 PM 2 replies 750+ views

Original Post

May 11, 2004 at 4:59 PM

I've a tempplated class CDrawRectangle, which has a function pointer to a function of this class:

template<class T>
class CDrawRectangle{

// function pointer to a member-function of this class

void (*DrawPixel)(int, int, int);

// one way to draw a pixel

void DrawPixelQuick(int x, int y, int color);

// another way to draw a pixel

void DrawPixelSlow(int x, int y, int color);

if I try to assign DrawPixel to one of the member function (within another member-function of CDrawRectangle) I get a syntax error: cannot convert from 'void (__thiscall CDrawRectangle::*)(int,int,int)' to 'void (__cdecl *)(int,int,int)' When I change the declaration of DrawPixel to: void (CDrawRectangle::*m_DrawPixel)(int, int, int); vc++ says "term does not evaluate to a function" and points to a line where I make an call to DrawPixel. It doesn't complain when I assign the member-function to the function-pointer. I don't understand why vc++ complains so much ;(, but I hope that my problem is clear and someone can give me some advice [edited by - Merwin on May 11, 2004 6:03:16 PM]

Jingo

May 11, 2004 at 5:05 PM


struct example
{
	void function(){}
};

int main()
{
	example one, *ptwo = &one
	void (example::*pfunction)(void) = &example::function;
	(one.*pfunction)();
	(ptwo->*pfunction)();
}

[edited by - Jingo on May 11, 2004 6:07:19 PM]

Archimage

May 11, 2004 at 5:09 PM

Beat me to it

Also it might be worth checking out

http://www.function-pointer.org/functor.html

which I found on an earlier thread (looks as though it covers the basics).

Yours,

Archimage
(Ann-Marie Ratcliffe)

[edited by - Archimage on May 11, 2004 6:10:06 PM]

rypyr

May 11, 2004 at 5:10 PM

boost::bind

[ CodeDread ]

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