plugable: Specify plugin base classes and modules using API properties

https://fedorahosted.org/freeipa/ticket/3090

Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>

ipalib/__init__.py

@@ -899,16 +899,16 @@ else:
 
 
 class API(plugable.API):
-    def __init__(self, allowed):
-        super(API, self).__init__(allowed, ['ipalib.plugins.*'])
-
-    def bootstrap(self, parser=None, **overrides):
-        super(API, self).bootstrap(parser, **overrides)
+    bases = (Command, Object, Method, Backend, Updater)
 
+    @property
+    def modules(self):
+        result = ('ipalib.plugins.*',)
         if self.env.in_server:
-            self.modules.append('ipaserver.plugins.*')
+            result += ('ipaserver.plugins.*',)
         if self.env.context in ('installer', 'updates'):
-            self.modules.append('ipaserver.install.plugins.*')
+            result += ('ipaserver.install.plugins.*',)
+        return result
 
 
 def create_api(mode='dummy'):
@@ -926,7 +926,7 @@ def create_api(mode='dummy'):
 
         - `backend.Backend`
     """
-    api = API((Command, Object, Method, Backend, Updater))
+    api = API()
     if mode is not None:
         api.env.mode = mode
     assert mode != 'production'

ipalib/plugable.py

@@ -306,24 +306,31 @@ class API(ReadOnly):
 
     register = Registrar()
 
-    def __init__(self, allowed, modules):
+    def __init__(self):
         super(API, self).__init__()
-        self.__plugins = {base: {} for base in allowed}
-        self.modules = modules
+        self.__plugins = {}
         self.__done = set()
         self.env = Env()
 
+    @property
+    def bases(self):
+        raise NotImplementedError
+
+    @property
+    def modules(self):
+        raise NotImplementedError
+
     def __len__(self):
         """
         Return the number of plugin namespaces in this API object.
         """
-        return len(self.__plugins)
+        return len(self.bases)
 
     def __iter__(self):
         """
         Iterate (in ascending order) through plugin namespace names.
         """
-        return (base.__name__ for base in self.__plugins)
+        return (base.__name__ for base in self.bases)
 
     def __contains__(self, name):
         """
@@ -614,10 +621,11 @@ class API(ReadOnly):
 
         # Find the base class or raise SubclassError:
         found = False
-        for (base, sub_d) in self.__plugins.iteritems():
+        for base in self.bases:
             if not issubclass(klass, base):
                 continue
 
+            sub_d = self.__plugins.setdefault(base, {})
             found = True
 
             if sub_d.get(klass.__name__) is klass:
@@ -647,7 +655,7 @@ class API(ReadOnly):
         if not found:
             raise errors.PluginSubclassError(
                 plugin=klass,
-                bases=self.__plugins.keys(),
+                bases=self.bases,
             )
 
     def finalize(self):
@@ -664,8 +672,9 @@ class API(ReadOnly):
         plugins = {}
         plugin_info = {}
 
-        for base, sub_d in self.__plugins.iteritems():
+        for base in self.bases:
             name = base.__name__
+            sub_d = self.__plugins.get(base, {})
 
             members = []
             for klass in sub_d.itervalues():

ipaserver/advise/base.py

@@ -121,7 +121,12 @@ class Advice(Plugin):
 
         raise NotImplementedError
 
-advise_api = API((Advice,), ('ipaserver.advise.plugins.*',))
+
+class AdviseAPI(API):
+    bases = (Advice,)
+    modules = ('ipaserver.advise.plugins.*',)
+
+advise_api = AdviseAPI()
 
 
 class IpaAdvise(admintool.AdminTool):

ipatests/test_ipalib/test_plugable.py

@@ -202,7 +202,11 @@ class test_API(ClassChecker):
             def method(self, n):
                 return n + 1
 
-        api = plugable.API([base0, base1], [])
+        class API(plugable.API):
+            bases = (base0, base1)
+            modules = ()
+
+        api = API()
         api.env.mode = 'unit_test'
         api.env.in_tree = True
         r = api.add_plugin