Moose-like object system for Python
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Latest commit cff6ede Aug 12, 2015 @frasertweedale bump version to 0.3



import elk

class Point(elk.Elk):
    x = elk.ElkAttribute(mode='rw', type=int)
    y = elk.ElkAttribute(mode='rw', type=int)

    def clear(self):
        self.x = 0
        self.y = 0

class Point3D(Point):
    z = elk.ElkAttribute(mode='rw', type=int)

    def clear_z(self):
        self.z = 0

What is Elk?

Elk (homepage) is an object system for Python inspired by Moose for Perl. It implements many of the features of Moose including:

  • attribute delegation
  • default attribute values
  • lazy attribute initialisation
  • read-only attributes
  • required attributes
  • attribute type constraints
  • roles
  • method modifiers

Elk is written in pure Python and there are no dependencies beyond the standard library.

How does Elk differ from Moose?

Moose has many features that are not (yet) implemented in Elk.

While Elk tries to faithfully implement Moose paradigms and patterns in Python, it uses Python idioms and language features as much as possible. There are also some differences in terminology in order to be consistent with Python terminology or idioms.

There is not yet a namespace for Elk extensions, nor any convenient mechanism for extending it.


pip install elk


Elk is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.


The Elk source code is available from

Bug reports, patches, feature requests, code review and documentation are welcomed.

To submit a patch, please use git send-email or generate a pull request. Write a well formed commit message. If your patch is nontrivial, update the copyright notice at the top of each changed file.