在python中实现weakref属性的描述符类
weakref_propert的Python项目详细描述
添加一个类似于普通属性的属性， 但对指定的任何内容都保持弱引用 为了它。
示例：
First let’s define WeakValue using WeakProperty and SomeClass that will be weakly referenced:
>>> import weakref_property >>> import gc >>> class WeakValue(object): ... value = weakref_property.WeakProperty('value') >>> class SomeClass(object): ... passYou can assign and retrieve a value:
>>> a = SomeClass() >>> obj = WeakValue() >>> obj.value = a >>> obj.value # doctest: +ELLIPSIS <__main__.SomeClass object at ...>But it is kept as a weakref, so it can get collected. If it is collected, the property returns None:
>>> del a >>> gc.collect() # force gc to collect `a` object 0 >>> obj.valueYou can also delete the value completelly:
>>> del obj.value >>> obj.value Traceback (most recent call last): ... AttributeError: 'WeakValue' object has no attribute 'value'Sadly, weakrefs do not work on tuples, ints and not-subclassed lists and dicts:
>>> obj.value = [] Traceback (most recent call last): ... TypeError: cannot create weak reference to 'list' object
欢迎加入QQ群-->： 979659372
