Arthur wrote:

Trying to handle the sudden change of state of an instance of an object - a "quantum instance"

c starts as a Circle instance.

Say, in the course of the manipulation of c its radius approaches towards infinity, and upon the radius becoming > than some Max, I want c to suddenly think of itself as a Line instance rather than as a Circle instance.

doable?

hints?

Art

As a sketch: class Blended(object): MaxRadius = 123456 def __init__(self, radius): self._active = Circle(radius=radius) self._other = Line() self.radius = radius # Switch to Line if necessary def __getattr__(self, name): return getattr(self._active, name) def __setattr__(self, name, value): if name[0] == '_': object.__setattr__(self, name, value) elif name[0] != 'radius': return setattr(self, value) if value < self.MaxRadius: if isinstance(self._active, Line): self._active, self._other = self._other, self._active else: if isinstance(self._active, Circle): self._active, self._other = self._other, self._active self._active.radius = value You could read up on __getattr__, __getattribute__, and friends in the Language References section 3.3.2: Customizing attribute access --Scott David Daniels Scott.Daniels@Acm.Org