I'm trying to write a simple game and decided I need an eventmanager.
<code>
import weakref
from collections import defaultdict
class _EventManager( object ):
def __init__( self ):
self._handled_events =
defaultdict( weakref.WeakKeyDictionary )
def register( self, handler, event_type, filter=None ):
self._handled_events[event_type][handler] = filter
def deregister( self, handler, event_type ):
self._handled_events[event_type].pop( handler, None )
def handle_event( self, event ):
event_type = event.type
for handler, filter in
self._handled_events[event_type].items():
if filter == None or filter(event):
handler( event )
eventmanager = _EventManager()
__all__ = [ eventmanager ]
</code>
Fairly simple, yet there was some strange bug that prevented my game
from exiting.
I think what happened was that when __init__ ends, self goes out of
scope, and by extension so does self.handle_quit, Now there are no
more refeences to self.handle_quit, because weakrefs don't count, and
the event gets automatically dropped from my eventmanager. I thought
that wouldn't happen because handle_quit is part of the class and
instance MainGame.
Am I right in my guess? If so, how should I adress this bug? If not,
what is the bug?
<code>
import pygame
from eventmanager import eventmanager
class MainGame( object ):
def __init__( self, width=1024, height=768 ):
#Initialize PyGame
pygame.init()
self.width = width
self.height = height
self.quit_game = False
#Create the Screen
self.screen = pygame.display.set_mode( ( self.width,
self.height ) )
eventmanager.register( self.handle_quit, pygame.QUIT )
eventmanager.register( self.handle_quit, pygame.KEYDOWN,
key_filter( pygame.K_ESCAPE ) )
def mainloop( self ):
handle_event = eventmanager.handle_event
self.quit_game = False
while not self.quit_game:
for event in pygame.event.get():
handle_event( event )
def handle_quit( self, event=None ):
self.quit_game = True
def key_filter( key ):
def filter( event ):
return event.key == key
return filter
def handle_print_event( event ):
print str( event )
if __name__ == "__main__":
game = MainGame()
game.mainloop()
</code>
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