double include

[hrva07]

I have classes Shape and Document.
Document holds Shapes.

Document has a list<Shape*> _shapes.
But I would like to have a pointer to Document in Shape, too.
And I would like to call some Document methods from Shape.

Here is short version of code:

document.h

include "shape.h"
class Document
{
  list<Shape*> _shapes;
  //...
}

shape.h

class Document;
class Shape
{
  document* _pointerToMyDocument;
  //...
}

Now when I call _pointerToMyDocument->SetSomething();
compilation fail with error:

invalid use of undefined type `struct Document'
forward declaration of `struct Document'

Do I nead to put #include "document.h" in Shape.

Is it ok to do next ??

document.h

include "shape.h"
class Document {}

shape.h

include "document.h"
class Shape {}

Because now there is double relationship...

[Peter87]

The solution is to put the forward declaration in the header files and the include in the source files.

[vlad from moscow]

Is it a typo?

class Document;
class Shape
{
  document* _pointerToMyDocument;
  //...
}

Now when I call _pointerToMyDocument->SetSomething();
compilation fail with error:

invalid use of undefined type `struct Document'
forward declaration of `struct Document'

I think that the code where you are using the call _pointerToMyDocument->SetSomething(); does not see yet the definition of class Document. Maybe you should place the code where you are using this call after the definition of class Document.

[hrva07]

Thank You for your comments..

I did it the way Peter87 says..