POX控制器源码阅读(二) 组件如何监听事件/未完成

目前看到的三种监听
listenTo
addListeners
listen_to_dependencies

首先了解一下pox/lib/revent下EventMixin类中的autoBindEvents方法
autoBindEvents为组件与事件绑定函数def autoBindEvents (sink, source, prefix='', weak=False, priority=None):
  if len(prefix) > 0 and prefix[0] != '_': prefix = '_' + prefix
if hasattr(source, '_eventMixin_events') is False:
# If source does not declare that it raises any events, do nothing
print("Warning: source class %s doesn't specify any events!" % (
source.__class__.__name__,))
return []

events = {}
for e in source._eventMixin_events:
if type(e) == str:
events[e] = e
else:
events[e.__name__] = e

listeners = []
# for each method in sink
for m in dir(sink):
# get the method object
a = getattr(sink, m)
if callable(a):
# if it has the revent prefix signature,
if m.startswith("_handle" + prefix + "_"):
event = m[8+len(prefix):]
# and it is one of the events our source triggers
if event in events:
# append the listener
listeners.append(source.addListener(events[event], a, weak=weak,
priority=priority))
#print("autoBind: ",source,m,"to",sink)
elif len(prefix) > 0 and "_" not in event:
print("Warning: %s found in %s, but %s not raised by %s" %
(m, sink.__class__.__name__, event,
source.__class__.__name__))

return listeners
我们来看一下autoBindEvents的功能
因为“sink”的对象常常会对一些其他source引发的事件感兴趣，因而autoBindEvents是用来为“source引发的事件”自动在“sink”中安装listener。
这需要你在sinl对象中对handler methods进行特殊的命名方法，比如当你有一个对象mySource用以产生多个事件，比如FooEvent和BarEvent，而你的mySink对象希望去监听这些事件，所以你必须要将你的handler method命名为如下方式:
"_handle_FooEvent","_handle_BarEvent"，之后只要调用autoBindEvents(mySink, mySource)就可以完成handlers的安装。
该函数也提供了额外的命名方式，比如按这种方式调用：autoBindEvents(mySink, mySource, "source1")。就可以将handlers的名字改为"_handle_source1_FooEvent"。

分析代码：
if len(prefix) > 0 and prefix[0] != '_': prefix = '_' + prefix

该句判断event是否有前缀
events = {}用于保存source的事件

listeners = [] 用来保存事件处理函数handlers
for m in dir(sink):
    a = getattr(sink, m)
    if callable(a):
        if m.startswith("_handle" + prefix + "_"):
            event = m[8+len(prefix):]
        if event in events:

          listeners.append(source.addListener(events[event], a, weak=weak, priority=priority))
便利组件中的函数，如果存在_handle_开头的函数，取出其事件名，如果事件名对应，则将该处理函数存储在source中