[Tutor] Descriptors and type declaration order

[Knacktus]

Hi guys,

I've got the following (not working) code:

class Attribute(object):

    def __init__(self, attribute_name, att_type_name):
        self._attribute_name = attribute_name
        try:
            self._attribute_type = globals()[att_type_name]
        except KeyError:
            self._attribute_type = getattr(globals()["__builtins__"],
att_type_name)

    def __get__(self, obj, obj_type):
        return getattr(obj, self._attribute_name)

    def __set__(self, obj, value):
        if isinstance(value, self._attribute_type):
            setattr(obj, self._attribute_name, value)
        else:
            raise ItemTypeException(self._attribute_type, type(value))

class BaseItem(object):

    ident = Attribute("ident", "int")
    owner = Attribute("owner", "str")
    item = Attribute("item", "BaseItem")

if __name__ == "__main__":
    print "About to create an item"
    test = BaseItem()
    print "OK"

The problem is that the descriptors are created when the module is
evaluated. But at this time the class BaseItem is not known yet. Any ideas?

Cheers,

Jan
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