Re: [Zope] Copying Objects of a Python Class

25 Apr 2002


      I solved it. I use the following lines for copying an object:

orig # the original (instance of MyClass())
copy=MyClass()
copy.__setstate__(orig.__getstate__())

  thomas

Thomas Guettler wrote:
...
Hi!
If I copy an instance of a python class (I am developing a python product)
I got the problem that it does a deep copy. The original
has a attribute called default_catalog which is
a reference to the catalog where all objects are stored.
If I do a copy, there is a unfortunately
a new object (default_catalog). But it should be a reference
to the catalog where all objects are stored.
I store a template in the folder 'defaults' and want
to copy it to 'documents'. (Layout: root/defaults root/documents)
In the Object which gets copied:
  def createNewDocument(self, REQUEST=None):
        r=self.root()
        orig=r.defaults[self.id]
        copy=orig._getCopy(r)
# Stolen form CopySupport.manage_clone. Don't know what it does
        copy=copy.__of__(orig)
copy.id=r.nextID()
        copy.isDefaultDocument=0
        r.documents._setObject(copy.id, copy) # TODO: Btree
        if copy.default_catalog!=orig.default_catalog:
            print "orig", orig.default_catalog
            print "copy", copy.default_catalog
            raise "Bad Copy"
        if REQUEST:
            REQUEST.RESPONSE.redirect('/' + r.id + '/documents/' + copy.id)
The log:
orig <ZCatalog instance at 02633AB8>
copy <ZCatalog instance at 02522EC0>
--> there is a new object
_getCopy does this (From Zope's CopySupport.py):
    def _getCopy(self, container):
        # Ask an object for a new copy of itself.
        f=tempfile.TemporaryFile()
        self._p_jar.exportFile(self._p_oid,f)
        f.seek(0)
        ob=container._p_jar.importFile(f)
        f.close()
        return ob
I think the export and reimport creates new objects.
I think I will write my own copy method and don't use _getCopy except
someone has a solution
Thank you for listening.
thomas