PyGame事件处理

Question

我刚开始玩游戏，我试着写我自己的事件管理器，因为我找不到我满意的解决方案。所以我写了我自己的灵感来自观察者模式：

from typing import Callable

from pygame.event import Event

EventHandler = Callable[[Event], None]

_managers = dict()


class EventManager:
    def __init__(self, name):
        self.name = name
        self.handlers: dict[int, list[EventHandler]] = dict()

    def notify(self, event: Event, selector=lambda event: event.type):
        eventType = selector(event)
        if eventType not in self.handlers:
            return

        for handler in self.handlers[eventType]:
            handler(event)

    def register(self, eventType: int, handler: EventHandler):
        print(f"{self.name} registered {eventType}")
        if eventType not in self.handlers:
            self.handlers[eventType] = [handler]
        else:
            self.handlers[eventType].append(handler)

    def deregister(self, eventType: int, handler: EventHandler):
        if not self._is_registered(eventType, handler):
            return
        self.handlers[eventType].remove(handler)

    def _is_registered(self, eventType, handler):
        return eventType in self.handlers and handler in self.handlers[eventType]

    @staticmethod
    def get(id: str):
        if id not in _managers:
            _managers[id] = EventManager(id)
        return _managers[id]


generalEventManager = EventManager.get("General Events")
keyEventManager = EventManager.get("Key Events")

它是这样用的：

class Foo:
    _running = True

    def register_events(self):
        generalEventManager.register(pygame.QUIT, lambda _: self.on_quit())
        generalEventManager.register(pygame.KEYDOWN, lambda event: self.on_key_down(event))
        # register key events with
        # keyEventManager.register(pygame.K_RETURN, lambda _: self.on_k_return())
        # ...

    def on_key_down(self, event: Event):
        keyEventManager.notify(event, selector=lambda event: event.key)

    def on_quit(self):
        self._running = False

    def on_cleanup(self):
        pygame.quit()

    def on_execute(self):
        while self._running:
            for event in pygame.event.get():
                self.on_event(event)
        self.on_cleanup()

这是毕多尼亚人吗？在游戏中有没有更好的解决方案？有没有我没有找到的通用python库解决方案？

Answer 1

这看上去相当像琵琶，并且很好地利用了观察者的模式。

我要说的一件事是，对于备用构造函数，您通常使用类方法而不是静态方法，然后调用'cls‘属性，而不是按名称调用类。如果您想要使用继承，这一点很重要，此外，出于同样的原因，您可能希望将您的_managers全局dict绑定到该类。

@classmethod
def get(cls, id: str):
    if id not in cls._managers:
        cls._managers[id] = cls(id)
    return cls._managers[id]

此外，您不需要每次都通过lambdas。您可以直接传递函数本身。

def register_events(self):
    generalEventManager.register(pygame.QUIT, self.on_quit)  # You'll need to modify the call signature here
    generalEventManager.register(pygame.KEYDOWN, self.on_key_down)
    # register key events with
    # keyEventManager.register(pygame.K_RETURN, self.on_k_return)
    # ...

您的名字有点不具有描述性，我可能会将您的'get‘方法称为'from_id’之类的方法，以表示清晰，而且很明显，'Foo‘应该更丰富一些。

我还将研究处理其他高阶函数的更好方法，而不是依赖lambdas。例如，可以尝试使用操作符模块：

from operator import attrgetter

# Code here

    def notify(self, event: Event, selector=attrgetter('type')):
        ...

此外，您可能希望使用默认的dict来稍微简化实现：

from collections import defaultdict
from operator import attrgetter


class EventManager:
    def __init__(self, name):
        self.name = name
        self.handlers: dict[int, list[EventHandler]] = defaultdict(list)

    def notify(self, event: Event, selector=attrgetter('type')):
        for handler in self.handlers[selector(event)]:
            handler(event)

    def register(self, eventType: int, handler: EventHandler):
        print(f"{self.name} registered {eventType}")
        self.handlers[eventType].append(handler)

    def deregister(self, eventType: int, handler: EventHandler):
        if handler in self.handlers[eventType]:
            self.handlers[eventType].remove(handler)

    @classmethod
    def from_id(cls, _id: str):
        if _id not in _managers:
            _managers[_id] = EventManager(_id)
        return _managers[_id]