173 lines
5.3 KiB
Python
173 lines
5.3 KiB
Python
#!/usr/bin/python
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# -*- coding: utf-8 -*-
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"""
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MVVM 小框架核心模块。
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这个根目录版本与 demo/mvvm/framework.py 作用相同，适合复制到其他项目中
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单独使用。它提供发布-订阅事件通道，以及 Model/View 的绑定入口。
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"""
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from threading import Thread, Lock
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from queue import Queue
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from enum import Enum, unique
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class Subscriber(object):
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"""订阅者：记录一个主题以及主题触发时要执行的回调函数。"""
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def __init__(self, topic, callback):
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# 订阅的事件主题。
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self._topic = topic
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# 主题事件发生时执行的函数。
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self._callback = callback
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@property
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def topic(self):
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"""返回订阅主题。"""
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return self._topic
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@property
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def callback(self):
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"""返回事件回调函数。"""
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return self._callback
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class Publisher(object):
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"""发布事件时放入队列的消息对象。"""
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def __init__(self, topic, content):
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# 事件主题，用于匹配订阅者。
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self._topic = topic
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# 事件内容，会作为参数传给订阅回调。
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self._content = content
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@property
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def topic(self):
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"""返回事件主题。"""
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return self._topic
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@property
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def content(self):
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"""返回事件内容。"""
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return self._content
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# 保留主题：当前没有使用，预留给未来的占位或空事件。
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KEEP_TOPIC = 'keep'
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class EventChannel(Thread):
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"""事件通道线程：从队列取事件，并分发给对应 topic 的订阅者。"""
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def __init__(self):
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super(EventChannel, self).__init__()
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# 控制线程循环。
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self._working = True
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# 保护订阅关系表的互斥锁。
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self._mutex = Lock()
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# 线程安全事件队列。
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self._queue = Queue()
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# topic 到订阅者列表的映射。
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self._resigster_container = {}
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def __del__(self):
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# 简单停止标记；demo 级写法，不保证立即唤醒阻塞中的 get()。
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self._working = False
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def run(self) -> None:
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"""线程主循环：消费事件并执行订阅回调。"""
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while self._working:
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puber = self._queue.get()
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with self._mutex:
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print('pop event {} : {}'.format(puber.topic, puber.content))
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group = self._resigster_container.get(puber.topic, [])
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for suber in group:
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suber.callback(puber.content)
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def publish(self, topic: str, content):
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"""发布事件：把 topic 和 content 包成 Publisher 放入队列。"""
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puber = Publisher(topic, content)
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self._queue.put(puber)
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def subscribe(self, topic: str, callback):
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"""订阅事件：登记 topic 与回调函数的关系。"""
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suber = Subscriber(topic, callback)
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with self._mutex:
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group = self._resigster_container.get(suber.topic, [])
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group.append(suber)
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self._resigster_container[suber.topic] = group
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class BaseModel(object):
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"""Model 基类：保存主题，并提供可被 View 事件调用的代理方法。"""
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def __init__(self, topic: str):
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# Model 变化时发布的主题。
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self._topic = topic
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@property
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def topic(self):
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"""返回 Model 对应主题。"""
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return self._topic
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def signal_proxy(self, *args):
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"""事件代理函数，具体 Model 可重写。"""
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print('{} event proxy run'.format(type(self)))
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class BaseView(object):
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"""View 基类：保存主题，并提供可被 Model 事件调用的代理方法。"""
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def __init__(self, topic: str):
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# View 变化时发布的主题。
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self._topic = topic
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@property
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def topic(self):
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"""返回 View 对应主题。"""
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return self._topic
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def signal_proxy(self, *args):
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"""事件代理函数，具体 View 可重写。"""
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print('{} event proxy run'.format(type(self)))
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@unique
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class BindingStyle(Enum):
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"""Model 与 View 的绑定方向。"""
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DOUBLE_BINDING = 0 # 双向绑定。
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MODEL_TO_VIEW = 1 # Model -> View。
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VIEW_TO_MODEL = 2 # View -> Model。
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class Framework(object):
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"""框架门面对象：负责启动通道和建立绑定。"""
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def __init__(self):
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# 框架内部唯一事件通道。
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self.channel = EventChannel()
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def work(self):
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"""启动事件通道线程。"""
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self.channel.daemon = True
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self.channel.start()
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def binding(self, model: BaseModel, view: BaseView, style=BindingStyle.DOUBLE_BINDING):
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"""按指定方向绑定 Model 与 View。"""
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if style == BindingStyle.DOUBLE_BINDING:
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self.channel.subscribe(model.topic, view.signal_proxy)
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self.channel.subscribe(view.topic, model.signal_proxy)
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elif style == BindingStyle.MODEL_TO_VIEW:
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# 模型改变引起视图改变。
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self.channel.subscribe(model.topic, view.signal_proxy)
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elif style == BindingStyle.VIEW_TO_MODEL:
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# 视图改变引起模型改变。
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self.channel.subscribe(view.topic, model.signal_proxy)
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else:
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raise RuntimeWarning('binding is wrong')
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# 框架单例对象，业务代码通过它发布、订阅和绑定。
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fw_proxy = Framework()
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