Did some initial work for Context plugins

ipalib/plugable.py

@@ -27,6 +27,7 @@ http://docs.python.org/ref/sequence-types.html
 
 import re
 import inspect
+import threading
 import errors
 from errors import check_type, check_isinstance
 from config import Environment, Env
@@ -705,6 +706,25 @@ class Registrar(DictProxy):
         self.__registered.add(klass)
 
 
+class LazyContext(object):
+    """
+    On-demand creation of thread-local context attributes.
+    """
+
+    def __init__(self, api):
+        self.__api = api
+        self.__context = threading.local()
+
+    def __getattr__(self, name):
+        if name not in self.__context.__dict__:
+            if name not in self.__api.Context:
+                raise AttributeError('no Context plugin for %r' % name)
+            value = self.__api.Context[name].get_value()
+            self.__context.__dict__[name] = value
+        return self.__context.__dict__[name]
+
+
+
 class API(DictProxy):
     """
     Dynamic API object through which `Plugin` instances are accessed.
@@ -715,6 +735,7 @@ class API(DictProxy):
         self.__done = set()
         self.register = Registrar(*allowed)
         self.env = Env()
+        self.context = LazyContext(self)
         super(API, self).__init__(self.__d)
 
     def __doing(self, name):