Question

I have two files, namely game.py and map.py. The following simplified code resides in them:

from PyQt4.QtGui import *
from PyQt4.QtCore import *

from datetime import *

from map import *

class Game:

    Scene = QGraphicsScene
    View = QGraphicsView


    @staticmethod
    def start():
        Game.App = QApplication(sys.argv)       
        Game.Scene=QGraphicsScene();    

        Game.Scene.setBackgroundBrush(QBrush(QColor(Qt.green)));

        Game.View=QGraphicsView(Game.Scene);
        print Game
        map=Map()

        Game.App.exec_()

if __name__=='__main__':
    Game.start()

and file map.py:

from PyQt4.QtCore import *
from PyQt4.QtGui import *
from game import *
class Map(QObject):
    def __init__(self,parent=None):
        super(Map,self).__init__(parent);
        print Game
        v=Game.View
        print v
        v.setWindowTitle("sth")

Running game.py results in

__main__.Game
game.Game
<class 'PyQt4.QtGui.QGraphicsView'>
Traceback (most recent call last):
  File "/home/abiusx/workspace/borj/trunk/game.py", line 119, in <module>
    Game.start()
  File "/home/abiusx/workspace/borj/trunk/game.py", line 66, in start
    map=Map()
  File "/home/abiusx/workspace/borj/trunk/map.py", line 16, in __init__
    v.setWindowTitle("asb")
TypeError: QWidget.setWindowTitle(QString): first argument of unbound method must have type 'QWidget'

The problem is, the code in map.py that references Game.View, detects it as a class (as defined in class body) but not what is overwritted on it (an actual instance).
Also Game is known as main.Game in game.py but as game.Game in map.py

Could anyone help me?

Answer 1

Whenever a file is read in Python, when it reaches a class definition it defines that class.

In my scenario, game and map both relied on each other. this is a well known circular reference problem in python.
I added another module, main.py, used game and map in it, and game in map. Problem solved.