x is not a class or namespace name

[soupsoup]

I have two classes Plugin and Display and Display inherits from Plugin. Plugin can't call a static Display method, how can I solve this? The Display class works fine elsewhere, and this all works fine with the line commented out.

#ifndef PLUGIN_H
#define PLUGIN_H

#include "Display.h"
#include "Data.h"

class Plugin
{
public:
	typedef void (*ptrToFunction)();
	virtual ptrToFunction getRenderPointer() = 0;
	virtual void editData(Data* data) = 0;

	void drawGraph()
	{
		Display::renderPointsGraph(); // This is the problem line
	}	
};

#endif 

#ifndef DISPLAY_H
#define DISPLAY_H

#include <stdlib.h>
#include <stdio.h>
#include <gl/glew.h>
#include <gl/glut.h>
#include <vector>;
#include <iostream>
#include <vector>
#include <sstream>
#include <string>

#include "Plugin.h"
#include "Data.h"
#include "GlutUI.h"

#define BUFFER_OFFSET(i) ((char*)NULL +(i))

class Display : public Plugin
{
private:
	const static float speed;
public:	
	static Data* data;
	static std::vector<GLuint>* bufferIDs;
	static float xRot, yRot;

	static void renderPointsGraph();
	static void drawMouseCoords();
	static void drawGraph();
	static void drawPoints();
	static void rotate(std::string axis, bool forwards);

	typedef void (*ptrToFunction)();
	ptrToFunction getRenderPointer()
	{
		return &(Display::renderPointsGraph);
	}
	void editData(Data* data) {}
};

#endif 

I can paste more code if necessary.

Thanks for any help!

[Disch]

You have an interdepencendy problem. Plugin.h is including Display.h and Display.h is including Plugin.h. That is problematic.

See section 4 and up: http://www.cplusplus.com/forum/articles/10627/#msg49679

To solve this, Plugin.h must not include Display.h until after the Plugin class is fully defined.

Here:

#ifndef PLUGIN_H
#define PLUGIN_H

//#include "Display.h"  // don't include this here
#include "Data.h"

class Plugin
{
public:
	typedef void (*ptrToFunction)();
	virtual ptrToFunction getRenderPointer() = 0;
	virtual void editData(Data* data) = 0;

	void drawGraph();
//	{  // don't inline this here
//		Display::renderPointsGraph();
//	}
};

/*

  Now that Plugin is fully defined, it is OK to include Display.h

*/

#include "Display.h"

inline void Plugin::drawGraph()  // now we can inline this
{
	Display::renderPointsGraph();
}

#endif  

[soupsoup]

Thanks for the reply. I tried your plugin fix but I am still getting the same errors. "'Display': is not a class or namespace name". "'renderPointsGraph': identifier not found".

[Disch]

Does Data.h include any of these headers? If so, it probably shouldn't.

You can't just have all your headers include each other. Careless including leads to trouble.

Really -- read section 4 here: http://www.cplusplus.com/forum/articles/10627/#msg49679

(EDIT: Section 7 is also on point)

It explains these problems and gives easy to follow guidelines as to how to avoid them.

[soupsoup]

No Data.h doesn't include any of them. It is included in another .cpp file, but that's so I can access one of Display's static functions. How else am I supposed to do that without including the header in the file?

[Disch]

Data.h must include it -- or maybe it includes something else that includes it. That's the only way I can make sense of the error.

In any event, upon further inspection, you don't need to include data.h at all:

#ifndef PLUGIN_H
#define PLUGIN_H

//#include "Data.h"  // don't do this

class Data;  // do this instead

class Plugin
{
public:
	typedef void (*ptrToFunction)();
	virtual ptrToFunction getRenderPointer() = 0;
	virtual void editData(Data* data) = 0;

	void drawGraph();
};

//==============================

#include "Display.h"

inline void Plugin::drawGraph()
{
	Display::renderPointsGraph();
}

#endif   

[soupsoup]

Ok now even without including data I have the same errors. This is frustrating.

[soupsoup]

Bump, any ideas anyone?

[coder777]

hello soupsoup,

well using names like Display, Plugin, and Data without surrounding/protecting namespaces are generally no good idea since it could be defined elsewhere.

if a line like #define Display whatever exists you're lost.


I'd suggest that you rename your Display to don't know maybe xxxxDisplay (all other accordingly) and see what happens

[soupsoup]

Thanks for the reply coder, I tried to replace Display with GLDisplay, but no luck, any other ideas?

[soupsoup]

Sorry to bump again but I really can't figure this out.

Edit: I moved the definition of drawGraph() into a seperate Plugin.cpp file and moved a few includes, and now it works!