summaryrefslogtreecommitdiffstats
path: root/meta/lib/oe/classutils.py
diff options
context:
space:
mode:
Diffstat (limited to 'meta/lib/oe/classutils.py')
-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 0000000..58188fd
--- /dev/null
+++ b/meta/lib/oe/classutils.py
@@ -0,0 +1,43 @@
1class ClassRegistry(type):
2 """Maintain a registry of classes, indexed by name.
3
4Note that this implementation requires that the names be unique, as it uses
5a dictionary to hold the classes by name.
6
7The name in the registry can be overridden via the 'name' attribute of the
8class, and the 'priority' attribute controls priority. The prioritized()
9method returns the registered classes in priority order.
10
11Subclasses of ClassRegistry may define an 'implemented' property to exert
12control over whether the class will be added to the registry (e.g. to keep
13abstract base classes out of the registry)."""
14 priority = 0
15 class __metaclass__(type):
16 """Give each ClassRegistry their own registry"""
17 def __init__(cls, name, bases, attrs):
18 cls.registry = {}
19 type.__init__(cls, name, bases, attrs)
20
21 def __init__(cls, name, bases, attrs):
22 super(ClassRegistry, cls).__init__(name, bases, attrs)
23 try:
24 if not cls.implemented:
25 return
26 except AttributeError:
27 pass
28
29 try:
30 cls.name
31 except AttributeError:
32 cls.name = name
33 cls.registry[cls.name] = cls
34
35 @classmethod
36 def prioritized(tcls):
37 return sorted(tcls.registry.values(),
38 key=lambda v: v.priority, reverse=True)
39
40 def unregister(cls):
41 for key in cls.registry.keys():
42 if cls.registry[key] is cls:
43 del cls.registry[key]