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authorChris Larson <chris_larson@mentor.com>2011-03-29 14:59:22 -0700
committerChris Larson <chris_larson@mentor.com>2011-05-18 09:43:12 -0700
commit95c1c690d14f493b615eafeb349d57aa67366b5d (patch)
treee0f72eb674c9cc39b42731138317af21d4bf3d08
parent1eb0207a7ae8cbc31ecde313a020ed4f12f70dd8 (diff)
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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>
-rw-r--r--meta/lib/oe/classutils.py43
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 0000000000..58188fdd6e
--- /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]