Skip to main content

A Descriptor class implementing weakref properties in Python

Project description

Add a property that acts like a normal attribute, but keeps a weak reference to anything that is assigned to it.


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):
...     pass

You 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
>>> obj.value

You 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

Project details

Release history Release notifications

This version
History Node


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Filename, size & hash SHA256 hash help File type Python version Upload date
weakref_property-0.1.tar.gz (14.4 kB) Copy SHA256 hash SHA256 Source None Aug 16, 2014

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging CloudAMQP CloudAMQP RabbitMQ AWS AWS Cloud computing Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page