From 3b97ea13c85870a1ff71312a42cd2c68036712a2 Mon Sep 17 00:00:00 2001 From: Chris Larson Date: Tue, 29 Mar 2011 14:59:22 -0700 Subject: oe.classutils: add module This adds a ClassRegistry utility metaclass, as maintaining a class registry is a fairly common thing to do. (From OE-Core rev: 6a46c375bea03b145bea41ec29ae2fd4d3cd9db6) Signed-off-by: Chris Larson Signed-off-by: Richard Purdie --- meta/lib/oe/classutils.py | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 meta/lib/oe/classutils.py (limited to 'meta/lib') 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] -- cgit v1.2.3-54-g00ecf