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author | Chris Larson <chris_larson@mentor.com> | 2011-03-29 14:59:22 -0700 |
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committer | Richard Purdie <richard.purdie@linuxfoundation.org> | 2011-06-28 13:53:13 +0100 |
commit | 6a46c375bea03b145bea41ec29ae2fd4d3cd9db6 (patch) | |
tree | 27126b838c274d94c645d76ec2f9ccd59d322834 /meta/lib/oe/classutils.py | |
parent | 1c8c893864afd91d4a0e5858bfe44ae9a4b33cef (diff) | |
download | openembedded-core-contrib-6a46c375bea03b145bea41ec29ae2fd4d3cd9db6.tar.gz |
oe.classutils: add module
This adds a ClassRegistry utility metaclass, as maintaining a class registry
is a fairly common thing to do.
Signed-off-by: Chris Larson <chris_larson@mentor.com>
Diffstat (limited to 'meta/lib/oe/classutils.py')
-rw-r--r-- | meta/lib/oe/classutils.py | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/meta/lib/oe/classutils.py b/meta/lib/oe/classutils.py new file mode 100644 index 00000000000..58188fdd6e0 --- /dev/null +++ b/meta/lib/oe/classutils.py @@ -0,0 +1,43 @@ +class ClassRegistry(type): + """Maintain a registry of classes, indexed by name. + +Note that this implementation requires that the names be unique, as it uses +a dictionary to hold the classes by name. + +The name in the registry can be overridden via the 'name' attribute of the +class, and the 'priority' attribute controls priority. The prioritized() +method returns the registered classes in priority order. + +Subclasses of ClassRegistry may define an 'implemented' property to exert +control over whether the class will be added to the registry (e.g. to keep +abstract base classes out of the registry).""" + priority = 0 + class __metaclass__(type): + """Give each ClassRegistry their own registry""" + def __init__(cls, name, bases, attrs): + cls.registry = {} + type.__init__(cls, name, bases, attrs) + + def __init__(cls, name, bases, attrs): + super(ClassRegistry, cls).__init__(name, bases, attrs) + try: + if not cls.implemented: + return + except AttributeError: + pass + + try: + cls.name + except AttributeError: + cls.name = name + cls.registry[cls.name] = cls + + @classmethod + def prioritized(tcls): + return sorted(tcls.registry.values(), + key=lambda v: v.priority, reverse=True) + + def unregister(cls): + for key in cls.registry.keys(): + if cls.registry[key] is cls: + del cls.registry[key] |