Make the 'cached' decorator work on methods.

[SVN r64640]

src/build/property_set.py

@@ -12,9 +12,11 @@ import b2.build.feature
 from b2.exceptions import *
 from b2.util.sequence import unique
 from b2.util.set import difference
+from b2.util import cached
 
 from b2.manager import get_manager
 
+
 def reset ():
     """ Clear the module state. This is mainly for testing purposes.
     """
@@ -427,7 +429,7 @@ class PropertySet:
         
         return self.feature_map_.get(feature, [])
 
-    # FIXME: make this cached
+    @cached
     def get_properties(self, feature):
         """Returns all contained properties associated with 'feature'"""
 

src/util/__init__.py

@@ -30,7 +30,10 @@ class cached(object):
         except KeyError:
             v = self.function(*args)
             self.cache[args] = v
-            return v    
+            return v
+
+    def __get__(self, instance, type):
+        return types.MethodType(self, instance, type)
 
 def unquote(s):
     if s and s[0] == '"' and s[-1] == '"':