python - 有没有比迭代相同循环更好的方法来检索值？

Question

简单来说，我有一个server的列表类，其中包含 component 的列表类，其中包含 function 的列表类。你知道这是怎么回事。

在我的程序中，我想从每个函数类中检索一个值，然后相互使用所有这些值，然后将结果值添加回 function类。我最终一遍又一遍地重复使用嵌套循环。

这是我的代码:

component_subscriptions = {}

for server in self.network.servers:
    for component in server.components:
        for function in component.functions:
            component_subscriptions[function.name] = []

for server in self.network.servers:
    for component in server.components:
        for function in component.functions:
            for subscription in function.subscriptions:
                if subscription.name in component_subscriptions.keys():
                    component_subscriptions[subscription.name].append(function.publish_address)

for server in self.network.servers:
    for component in server.components:
        for function in component.functions:
            print(function.name)
            if function.name in component_subscriptions.keys():
                function.subscribers.extend(component_subscriptions[function.name])

for server in self.network.servers:
    for component in server.components:
        for function in component.functions:
            if function.name in component_subscriptions.keys():
                function.subscribers = component_subscriptions[function.name]

有没有办法重用或简化三层for循环？我是否遗漏了一些明显可笑的东西？

Answer 1

使用生成器的直接方法:

def gen_functions(self):
    for server in self.network.servers:
        for component in server.components:
            for function in component.functions:
                yield function

for function in gen_functions(self):
    component_subscriptions[function.name] = []

for function in gen_functions(self):
    for subscription in function.subscriptions:
       if subscription.name in component_subscriptions.keys():
           component_subscriptions[subscription.name].append(function.publish_address)
...

关于第二个循环，我更喜欢这种方式:

for function in gen_functions(self):
    for subscription in (component_subscriptions[s.name] for s in function.subscriptions if s.name in component_subscriptions):
        subscription.append(function.publish_address)

要重用它，请创建另一个函数:

def iter_function_subscriptions(function):
    for subscription in (component_subscriptions[s.name] for s in function.subscriptions if s.name in component_subscriptions):
        yield subscription

所以现在将它们组合起来:

for function in gen_funtions(self):
   for subscription in iter_function_subscriptions(function):
       subscriptoin.append(function.publish_address)

已经完成，但您可能想将它们添加到函数类中。

# patching the class. it will be better if you can directly add this method into function class
type(function).iter_subscriptions = iter_function_subscriptions

那么，

for function in gen_funtions(self):
   for subscription in function.iter_subscriptions():
       subscription.append(function.publish_address)