[Zope] Multiple inheritance and tree data structure problems

[Manuel_Montejo@apb.es]

Hi,

I'm developing a Zope product, ServiceProduct,  that behaves as a Node in a
Tree data structure.

The class hierachy is the following    [<--- : extends ; <- - - :
implements]

Base <---Tree <- - -TreeImpl
Base <---- TreeNode <- - -  TreeNodeImpl
Base <---- Service

Implicit,Persistent,RoleManager,ObjectManager,PropertyManager,Item <----
ProductBase
ProductBase, TreeNodeImpl<---- ServiceProduct
TreeNode<- - - ServiceProduct
Service<- - - ServiceProduct

So, when I create an new instance of ServiceProduct using the ZMI I found a
problem with the constructor. The
error message is
     "unbound method __init__() must be called with instance as first
argument"
and the code is

    def __init__(self, id):
        ProductBase.__init__(self,id,'')
        try:
            TreeNodeImpl.__init__(self,id)
        except Exception, e:
            print 'Problems with TreeNodeImpl constructor', e
            # do TreeNodeImpl initialization here if fails
            self.setNombre( id )
            self.parentNode = None
            self.children = []
            self.tree = None

I hope that doing the TreeNodeImpl initialization in the except clause will
solve this problem.

Then, I add child ServiceProduct objects to the tree hierarchy but it seems
that the references between parent
and child objects change when new calls to the object are done (I use a
DTML page for displaying hierarchy info).

Even worse, the ProductBase has a method hashCode that shows instance info

    def hashCode(self):
        id = str( self )
        id = id.replace( '<', '_')
        id = id.replace( '>', '_')
        id = id.replace( ' ', '_')
        return id

returns two different results when is called from a DTML page, (sometimes
the first and other times the second),
BUT I have created only one instance of the object.

Finally, I have tested the TreeImpl, TreeNodeImpl outside Zope and it works
without any problems.

Any idea of where is the problem? The 'constructor problem' is related to
the 'references losing' problem?
Any help with will be apreciated.

Best regards,

Manu