| import collections |
| import weakref |
| |
| |
| class RemovableHandle(object): |
| """A handle which provides the capability to remove a hook.""" |
| |
| next_id = 0 |
| |
| def __init__(self, hooks_dict): |
| self.hooks_dict_ref = weakref.ref(hooks_dict) |
| self.id = RemovableHandle.next_id |
| RemovableHandle.next_id += 1 |
| |
| def remove(self): |
| hooks_dict = self.hooks_dict_ref() |
| if hooks_dict is not None and self.id in hooks_dict: |
| del hooks_dict[self.id] |
| |
| def __getstate__(self): |
| return (self.hooks_dict_ref(), self.id) |
| |
| def __setstate__(self, state): |
| if state[0] is None: |
| # create a dead reference |
| self.hooks_dict_ref = weakref.ref(collections.OrderedDict()) |
| else: |
| self.hooks_dict_ref = weakref.ref(state[0]) |
| self.id = state[1] |
| RemovableHandle.next_id = max(RemovableHandle.next_id, self.id + 1) |
| |
| def __enter__(self): |
| return self |
| |
| def __exit__(self, type, value, tb): |
| self.remove() |
