Did some initial work for Context plugins

ipa_server/plugins/b_ldap.py

@@ -25,13 +25,24 @@ This wraps the python-ldap bindings.
 """
 
 import ldap as _ldap
-from ipalib import api
+from ipalib import api, Context
 from ipalib import errors
 from ipalib.crud import CrudBackend
 from ipa_server import servercore
 from ipa_server import ipaldap
 
 
+class conn(Context):
+    """
+    Thread-local LDAP connection.
+    """
+
+    def get_value(self):
+        return 'it worked'
+
+api.register(conn)
+
+
 class ldap(CrudBackend):
     """
     LDAP backend plugin.

ipalib/__init__.py

@@ -30,15 +30,18 @@ To learn about the ``ipalib`` library, you should read the code in this order:
 """
 
 import plugable
-import frontend
-import backend
-import config
+from backend import Backend, Context
+from frontend import Command, Object, Method, Property, Application
+from ipa_types import Bool, Int, Unicode, Enum
+from frontend import Param, DefaultFrom
 
-api = plugable.API(
-    frontend.Command,
-    frontend.Object,
-    frontend.Method,
-    frontend.Property,
-    frontend.Application,
-    backend.Backend,
-)
+def get_standard_api(unit_test=False):
+    api = plugable.API(
+        Command, Object, Method, Property, Application,
+        Backend, Context,
+    )
+    if unit_test is True:
+        api.env.mode = 'unit_test'
+    return api
+
+api = get_standard_api()

ipalib/backend.py

@@ -23,9 +23,23 @@ Base classes for all backed-end plugins.
 
 import plugable
 
+
 class Backend(plugable.Plugin):
     """
     Base class for all backend plugins.
     """
 
     __proxy__ = False # Backend plugins are not wrapped in a PluginProxy
+
+
+class Context(plugable.Plugin):
+    """
+    Base class for plugable context components.
+    """
+
+    __proxy__ = False # Backend plugins are not wrapped in a PluginProxy
+
+    def get_value(self):
+        raise NotImplementedError(
+            '%s.get_value()' % self.__class__.__name__
+        )

ipalib/cli.py

@@ -331,7 +331,7 @@ class CLI(object):
                 if len(a) < 2:
                     parser.error('badly specified environment string,'\
                             'use var1=val1[,var2=val2]..')
-                overrides[a[0].strip()] = a[1].strip()
+                overrides[str(a[0].strip())] = a[1].strip()
         overrides['context'] = 'cli'
         self.api.bootstrap(**overrides)
 

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):

tests/test_ipalib/test_backend.py

@@ -22,12 +22,12 @@ Test the `ipalib.backend` module.
 """
 
 from ipalib import  backend, plugable, errors
-from tests.util import ClassChecker
+from tests.util import ClassChecker, raises
 
 
 class test_Backend(ClassChecker):
     """
-    Test the `backend.Backend` class.
+    Test the `ipalib.backend.Backend` class.
     """
 
     _cls = backend.Backend
@@ -35,3 +35,21 @@ class test_Backend(ClassChecker):
     def test_class(self):
         assert self.cls.__bases__ == (plugable.Plugin,)
         assert self.cls.__proxy__ is False
+
+
+class test_Context(ClassChecker):
+    """
+    Test the `ipalib.backend.Context` class.
+    """
+
+    _cls = backend.Context
+
+    def test_get_value(self):
+        """
+        Test the `ipalib.backend.Context.get_value` method.
+        """
+        class Subclass(self.cls):
+            pass
+        o = Subclass()
+        e = raises(NotImplementedError, o.get_value)
+        assert str(e) == 'Subclass.get_value()'