Source code for brian2.core.tracking

from collections import defaultdict
from weakref import ref

__all__ = ['Trackable']

[docs]class InstanceTrackerSet(set): ''' A `set` of `weakref.ref` to all existing objects of a certain class. Should not normally be directly used. '''
[docs] def add(self, value): ''' Adds a `weakref.ref` to the ``value`` ''' # The second argument to ref is a callback that is called with the # ref as argument when the object has been deleted, here we just # remove it from the set in that case wr = ref(value, self.remove) set.add(self, wr)
[docs] def remove(self, value): ''' Removes the ``value`` (which should be a weakref) if it is in the set Sometimes the value will have been removed from the set by `clear`, so we ignore `KeyError` in this case. ''' try: set.remove(self, value) except KeyError: pass
[docs]class InstanceFollower(object): """ Keep track of all instances of classes derived from `Trackable` The variable ``__instancesets__`` is a dictionary with keys which are class objects, and values which are `InstanceTrackerSet`, so ``__instanceset__[cls]`` is a set tracking all of the instances of class ``cls`` (or a subclass). """ instance_sets = defaultdict(InstanceTrackerSet)
[docs] def add(self, value): for cls in value.__class__.__mro__: # MRO is the Method Resolution Order which contains all the superclasses of a class self.instance_sets[cls].add(value)
[docs] def get(self, cls): return self.instance_sets[cls]
[docs]class Trackable(object): ''' Classes derived from this will have their instances tracked. The `classmethod` `__instances__()` will return an `InstanceTrackerSet` of the instances of that class, and its subclasses. ''' __instancefollower__ = InstanceFollower() # static property of all objects of class derived from Trackable def __new__(typ, *args, **kw): obj = object.__new__(typ) obj.__instancefollower__.add(obj) return obj @classmethod def __instances__(cls): return cls.__instancefollower__.get(cls)