YA-Newbie: baffled by deepcopy/pickle issues...

[Fred Pacquier]

Hi,

I'm working on my first sizable app in Python/wxPython, and I was making 
good progress until I hit this snag.

I want to be able to capture (to memory) the state of the app at a given 
time and restore it later if need be. Luckily most of that state is 
encompassed by a single object, so I thought copy.deepcopy() was going to 
be a snap.

Problem is, it only works once. I can save the current state, do a bunch of 
things, and go back to the saved state, all right. But if I try to restore 
it a second time, or try to save another one, everything goes to hell, as 
if the objects were empty.

It's a card game, with the object structure like this :

class Card : usual data attributes (color, rank, source bitmap, etc)
class Stack: mostly a List of Cards, plus a few attributes, and methods

self.Cols : an attribute of the wxFrame, a List of 13 Stacks, which 
encapsulates most of the game state.

Then I have methods like:

def Save(self, event):
    	self.SaveGame = deepcopy(self.Cols)

def Restore(self, event):
    	self.Cols = deepcopy(self.SaveGame)

All classes are defined at the top-level of the module. At first I thought 
I had misunderstood something about the function, so after trying a few 
variants I replaced deepcopy by pickle.dump() and pickle.load() with a temp 
file on disk. The behaviour is exactly the same, so maybe I have a general 
namespace/scope problem here...

Any hints on how to track this one down ? Thanks,
fp

-- 
YAFAP : http://www.multimania.com/fredp/