What is the common technique used to cross-reference in module's method?

Thu Mar 17 06:48:46 EDT 2016

There are two modules (say model.py and piece.py) which has methods need to refer to each other module's methods. I saw in a book using the way below, by assigning one (the Model) object to an attribute of the other (the Piece) bject.
-------------
##model.py
import piece
...
class Model(dict):
 ...
 def all_occupied_positions(self):
 ...
 def reset_to_initial_locations(self):
 self.clear()
 for position, value in START_PIECES_POSITION.items():
 self[position] = piece.create_piece(value)
 self[position].model = self
 ...
##piece.py
...
def create_piece(value): # Note: it's a function
 ...
 return eval(...) # the returned object is a Piece object
class Piece():
 ...
 def moves_available(self):
 model = self.model
 ...
 if item not in model.all_occupied_positions():
 ...
 ...
-----------
Is it a common way of doing this?
Why the author use the same module name "model" for those attribute and local names? Is it a good idea or bad?
--Jach