At 03:44 PM 10/20/01 +0200, Godefroid Chapelle wrote: >Hi, > >In a product I am writing, I am trying to add a ComputedAttribute to an >instance of a Folder descendant class. > >This is the code I use: > > def addComputedAttribute(self, attributeName, sourceCode): > methodName = '_ca_get%s' % attributeName > self.addMethod(methodName, sourceCode) > setattr(self, attributeName, > ContextComputedAttribute(self.__class__.__dict__[methodName]))
I think the problem you're having is that the method object being used in the last line (i.e., self.__class__.__dict__[methodName]) is not persistent. If it is a Python function, it will not be saved persistently within the computed attribute. This is probably why the Zope instance crashes at a later time. This doesn't have anything to do with whether ComputedAttribute is Persistent. It doesn't need to be, which is a good thing because you can't derive a class from both (as you've discovered). You can write a Python version of ComputedAttribute by deriving only from Persistent, but as I said there is really no need to do that. You need the function to be persistent, not the ComputedAttribute itself. If the function is currently a pure-Python function, you need to replace it with some kind of callable object that can be pickled, such as a PythonScript. You could also write your own class to do this, but again it is not the ComputedAttribute part that would cause a problem. _______________________________________________ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
