nzbToMedia/libs/jaraco/classes/meta.py
Labrys of Knossos 8d43b8ea39 Update jaraco-windows to 3.9.2
Also updates:
- importlib-metadata-0.7
- jaraco-windows
- jaraco.classes-1.5
- jaraco.collections-1.6.0
- jaraco.functools-1.20
- jaraco.structures-1.1.2
- jaraco.text-1.10.1
- jaraco.ui-1.6
- more-itertools-4.3.0
- path.py-11.5.0
- six-1.12.0
2018-12-15 15:06:37 -05:00

41 lines
943 B
Python

"""
meta.py
Some useful metaclasses.
"""
from __future__ import unicode_literals
class LeafClassesMeta(type):
"""
A metaclass for classes that keeps track of all of them that
aren't base classes.
"""
_leaf_classes = set()
def __init__(cls, name, bases, attrs):
if not hasattr(cls, '_leaf_classes'):
cls._leaf_classes = set()
leaf_classes = getattr(cls, '_leaf_classes')
leaf_classes.add(cls)
# remove any base classes
leaf_classes -= set(bases)
class TagRegistered(type):
"""
As classes of this metaclass are created, they keep a registry in the
base class of all classes by a class attribute, indicated by attr_name.
"""
attr_name = 'tag'
def __init__(cls, name, bases, namespace):
super(TagRegistered, cls).__init__(name, bases, namespace)
if not hasattr(cls, '_registry'):
cls._registry = {}
meta = cls.__class__
attr = getattr(cls, meta.attr_name, None)
if attr:
cls._registry[attr] = cls