[Zope] Subclassing Confusion

[Michel Pelletier]

> -----Original Message-----
> From: James W. Howe [mailto:jwh@allencreek.com]

> 
> What do I need to do to have the name "RenderableImage" in my 
> base class 
> list instead of two "Image" entries?

Your RenderableImage class inherits meta_type from Image, which is why
there apear to be two Image classes.  You have two of them because they
both look identical to Zope, you have essentially taken a rich class and
created another rich class with a little extra functionality.  Both of
these objects have the meta_type 'Image', for example, which is why you
see two of them with the same name in the class list.  They are
different classes, but they have very similar meta-data associated with
them.

What you should do is create a very thin python class which you MIX-IN
along with the rich Image class into a new ZClass with a new meta_type.
So instead of:

        Image->YourClass

You have:

            Image     \
                        -> YourClass
	  ThinBaseClass /

Where 'ThinBaseClass' defines your new __str__ method and mixes this
with the existing Image class into a new ZClass (with a new meta_type).
Your thin base class can be very thin indeed:

class ThinBaseClass:

  def __str__(self):
    ## whatever...
    pass

-Michel

-Michel