Allowing plugins to talk to eachother?

Helper

On 15/01/2013 at 09:07, xxxxxxxx wrote:

Wow.That's really great.
Thanks a lot Niklas.

Sorry it took up so much of your time.

-ScottA

Helper

On 25/01/2013 at 08:58, xxxxxxxx wrote:

Has anyone ever used friend classes within these C4D plugins?
In some cases it would be much less complicated if the two plugins simply had access to each others class members. Rather than using a third party interface to make them communicate.

I've Googled about friend classes trying to learn how to write them.
But when I try to use them inside of these plugins. I can't get it to work.
I can set up the basic framework so it will compile without errors. But when I try to access the member variables from the other class. I get undefined type errors.

Example:

  
//Forward declare the tag so the Dialog can access it  
class MyTag;  
  
class MyDialog : public GeDialog  
{  
  public:   
      virtual blah, blah, blah;  
      virtual blah, blah, blah;  
    
      LONG dialogMemberVariable;  //A class member that the tag can also access  
  
      friend MyTag;  
  
};  
...  
  
//How do I access use the tagMemberVariable without getting undefined class errors?  
  
  
class MyTag : public TagData  
{  
  public:  
      virtual blah, blah, blah;  
      virtual blah, blah, blah;  
    
      LONG tagMemberVariable; //A class member that the dialog can also access  
  
      friend MyDialog;   
};  
  
  //How do I access use the dialogMemberVariable without getting undefined class errors?  
  
...

-ScottA

Helper

On 27/01/2013 at 11:59, xxxxxxxx wrote:

Hi Scott,

The friend keyword allows the specified class to access protected and private attributes and
methods. Both of your classes have public members only, the friend keyword does not have any
effect.

Best,
Nik

Helper

On 27/01/2013 at 13:42, xxxxxxxx wrote:

Hiya Nik,

I learned a bit more about how to use friend yesterday.
I've a good raw C++ example now that I'm using as a learning tool:

//This is an example of using a custom method to access two different class's members  
//By making the method a friend of both of the classes  
  
#include <iostream>  
#include <string>  
using namespace std;  
  
class Class2;     //Forward declare Class2 so Class1 knows what's inside of it   
  
class Class1  
{  
  public:  
    int a, b;  
    Class1() : a(1), b(2) { }    //Constructor sets the class variable values  
    friend void change(Class1 c1, Class2 c2);  
};  
  
class Class2  
{  
  public:  
    int j;  
    Class2() : j(3) { }        //Constructor sets the class variable value  
    friend void change(Class1 c1, Class2 c2);   
};  
  
void change(Class1 &x1, Class2 &x2)  
{  
  x1.a = 10;          //Changes the Class1 variable from 1 to 10  
  x2.j = 45;        //Changes the Class2 variable from 3 to 45  
  
      //Compare the members from the two different classes  
  if(x1.a < x2.j) cout << "Class1 member a is less than Class2 member j" <<endl;  
}  
  
int main()  
{  
  Class1 c1;  
  Class2 c2;  
  change(c1,c2);  
  
  cout<< "Class1 member a= "<< c1.a <<endl;  
  cout<< "Class2 member j= "<< c2.j <<endl;  
  
  system("pause");   //Keeps the console open until the Enter key is pressed  
  return 0;  
}

The problem I'm having with this in C4D plugins is that we don't use main() quite the same way as in raw C++.
I think I need to place a prototype of the function that's the friend of the classes in the main.cpp file of C4D plugins. But I'm having a problem with the parameters part.

I can make a void type prototyped method without any parameters work fine in the C4D main.cpp file.
But when the method has params. in it ( In this cases the two classes). I'm having a hard time getting that to work in the main.cpp file.

-ScottA

Helper

On 27/01/2013 at 14:04, xxxxxxxx wrote:

Hi Scott,

I'm a little-bit confused. You never call the method check() of either class. The methods are defined,
but not implemented, nor ever referenced. What should this example actually demonstrate?

class A {
    friend B;
    private:

        void DoPrivateStuff();

    public:

        void DoPublicStuff();
};

class B {
    private:

        void DoPrivateStuff();

    public:

        void DoPublicStuff();
};

While class A has access to B::DoPublicStuff() only, class B has access to A::DoPublicStuff()
and A::DoPrivateStuff().

-Nik

Helper

On 27/01/2013 at 14:16, xxxxxxxx wrote:

Oops. Sorry about that.
"check" should be "changed".
I changed it.

The problem I'm having is calling the changed() type function when doing it in a C4D plugin.
main() is written slightly differently in these C4D plugins. And I'm having a problem with those differences.
Specifically. I'm having a hard time prototyping functions that have params. in them in the C4D main.cpp file.

-ScottA