Friend Functions in Namespaces.

I'm having a bit of a declarations Problem and I can't seem to get the right order of declarations.

I have a class, "DisplayTree" which represents various things to be drawn on an HDC.


The DisplayTrees are Drawn using an array of functions
DrawDisplayTreeFunctions[] which are not part of the class but are friends with it. And as I need lots of seperate functions to fill the Array I'd rather stow them all away in a namespace.

So Far So Good, I just do this.

Code:

---



//Declarations of array Functions in a Namespace
namespace nDrawDisplayTreeFunctions
{

    void ArrayFunction1(void);
    void ArrayFunction2(void);
    void ArrayFunction3(void);
    void ArrayFunction4(void);
    void ArrayFunction5(void);

}

//Function Array With Functions In it
void (* DrawDisplayTreeFunctions[]) (void) =
{
        nDrawDisplayTreeFunctions::ArrayFunction1,
        nDrawDisplayTreeFunctions::ArrayFunction2,
        nDrawDisplayTreeFunctions::ArrayFunction3,
        nDrawDisplayTreeFunctions::ArrayFunction4,
        nDrawDisplayTreeFunctions::ArrayFunction5
};




class DisplayTree
{


    friend void nDrawDisplayTreeFunctions::ArrayFunction1(void);
    friend void nDrawDisplayTreeFunctions::ArrayFunction2(void);
    friend void nDrawDisplayTreeFunctions::ArrayFunction3(void);
    friend void nDrawDisplayTreeFunctions::ArrayFunction4(void);
    friend void nDrawDisplayTreeFunctions::ArrayFunction5(void);


    //Other class members

};


namespace nDrawDisplayTreeFunctions
{

    void ArrayFunction1(void)
    {

        //Function definition

    }


    void ArrayFunction2(void)
    {

        //Function definition

    }


    void ArrayFunction3(void)
    {

        //Function definition

    }


    void ArrayFunction4(void)
    {

        //Function definition

    }


    void ArrayFunction5(void)
    {

        //Function definition

    }

}

---

And That's all Lovely The Array Functions can get at the protected members of the class and they're all tucked away in a namespace where they can't be called willy nilly.

The trouble is I want the functions to take a *DisplayTree as a parameter. Which causes problems, because I have to Declare the Functions inside the namspace before I define the class so I can make them friends. And I have to declare the class before I declare the functions So they can take a *DisplayTree as a Parameter. Can Anyone see a way around this Problem?

help.

Why not put a

Code:

---

class DisplayTree;

---

at the top? That will tell the compiler that there is code for that, but it can't have it just yet.

Thanks parksie.

I didn't realise yu could do that for classes.

what is the advantage of using namespaces?

namespaces will keep your code organized, but mostly theyre good for preventing name collisions between included files.

See the STL. For example, whenever anyone uses something from the STL, you often see "using namespace std;". You shouldn't really do that but it's okay for .cpp files. However, you should never import a whole namespace into a header file. If you use it in a source file the names are only imported for that file so you can keep track easier.