我和一个朋友一直在玩 pygame，偶然发现了这个使用 pygame构建游戏的教程。我们真的很喜欢它如何将游戏分解成一个模型-视图-控制器系统，其中事件作为中间人，但是代码大量使用了isinstance对事件系统的检查。
例子：
class CPUSpinnerController:
...
def Notify(self, event):
if isinstance( event, QuitEvent ):
self.keepGoing = 0
这会导致一些极其不合 Python 的代码。有人对如何改进有任何建议吗？或者实现 MVC 的替代方法？
这是我根据@Mark-Hildreth 回答编写的一些代码（我如何链接用户？）还有其他人有什么好的建议吗？在选择解决方案之前，我将把它打开一天左右。
class EventManager:
def __init__(self):
from weakref import WeakKeyDictionary
self.listeners = WeakKeyDictionary()
def add(self, listener):
self.listeners[ listener ] = 1
def remove(self, listener):
del self.listeners[ listener ]
def post(self, event):
print "post event %s" % event.name
for listener in self.listeners.keys():
listener.notify(event)
class Listener:
def __init__(self, event_mgr=None):
if event_mgr is not None:
event_mgr.add(self)
def notify(self, event):
event(self)
class Event:
def __init__(self, name="Generic Event"):
self.name = name
def __call__(self, controller):
pass
class QuitEvent(Event):
def __init__(self):
Event.__init__(self, "Quit")
def __call__(self, listener):
listener.exit(self)
class RunController(Listener):
def __init__(self, event_mgr):
Listener.__init__(self, event_mgr)
self.running = True
self.event_mgr = event_mgr
def exit(self, event):
print "exit called"
self.running = False
def run(self):
print "run called"
while self.running:
event = QuitEvent()
self.event_mgr.post(event)
em = EventManager()
run = RunController(em)
run.run()
这是使用来自@Paul 的示例的另一个构建 - 非常简单！
class WeakBoundMethod:
def __init__(self, meth):
import weakref
self._self = weakref.ref(meth.__self__)
self._func = meth.__func__
def __call__(self, *args, **kwargs):
self._func(self._self(), *args, **kwargs)
class EventManager:
def __init__(self):
# does this actually do anything?
self._listeners = { None : [ None ] }
def add(self, eventClass, listener):
print "add %s" % eventClass.__name__
key = eventClass.__name__
if (hasattr(listener, '__self__') and
hasattr(listener, '__func__')):
listener = WeakBoundMethod(listener)
try:
self._listeners[key].append(listener)
except KeyError:
# why did you not need this in your code?
self._listeners[key] = [listener]
print "add count %s" % len(self._listeners[key])
def remove(self, eventClass, listener):
key = eventClass.__name__
self._listeners[key].remove(listener)
def post(self, event):
eventClass = event.__class__
key = eventClass.__name__
print "post event %s (keys %s)" % (
key, len(self._listeners[key]))
for listener in self._listeners[key]:
listener(event)
class Event:
pass
class QuitEvent(Event):
pass
class RunController:
def __init__(self, event_mgr):
event_mgr.add(QuitEvent, self.exit)
self.running = True
self.event_mgr = event_mgr
def exit(self, event):
print "exit called"
self.running = False
def run(self):
print "run called"
while self.running:
event = QuitEvent()
self.event_mgr.post(event)
em = EventManager()
run = RunController(em)
run.run()