Python supports weak references as first-class objects. There are two specific object types which directly implement weak references. The first is a simple reference object, and the second acts as a proxy for the original object as much as it can.
返回 True 若 ob is either a reference or proxy object.
2.2 版新增。
返回 True 若 ob is a reference object.
2.2 版新增。
返回 True 若 ob is a proxy object.
2.2 版新增。
Return a weak reference object for the object ob . This will always return a new reference, but is not guaranteed to create a new object; an existing reference object may be returned. The second parameter, callback , can be a callable object that receives notification when ob is garbage collected; it should accept a single parameter, which will be the weak reference object itself. callback 还可以为 None or NULL 。若 ob is not a weakly-referencable object, or if callback is not callable, None ，或 NULL , this will return NULL and raise TypeError .
2.2 版新增。
Return a weak reference proxy object for the object ob . This will always return a new reference, but is not guaranteed to create a new object; an existing proxy object may be returned. The second parameter, callback , can be a callable object that receives notification when ob is garbage collected; it should accept a single parameter, which will be the weak reference object itself. callback 还可以为 None or NULL 。若 ob is not a weakly-referencable object, or if callback is not callable, None ，或 NULL , this will return NULL and raise TypeError .
2.2 版新增。
Return the referenced object from a weak reference, ref . If the referent is no longer live, returns Py_None .
2.2 版新增。
警告
This function returns a 借位引用 to the referenced object. This means that you should always call Py_INCREF() on the object except if you know that it cannot be destroyed while you are still using it.
类似于 PyWeakref_GetObject() , but implemented as a macro that does no error checking.
2.2 版新增。
