frontend: merge baseldap.CallbackRegistry into Command

Also make it possible for subclasses to introduce new callback types.

https://fedorahosted.org/freeipa/ticket/4739

Reviewed-By: David Kupka <dkupka@redhat.com>

ipalib/frontend.py

@@ -369,6 +369,9 @@ class HasParam(Plugin):
         return context.current_frame
 
 
+_callback_registry = {}
+
+
 class Command(HasParam):
     """
     A public IPA atomic operation.
@@ -390,6 +393,14 @@ class Command(HasParam):
     ['my_command']
     >>> api.Command.my_command # doctest:+ELLIPSIS
     ipalib.frontend.my_command()
+
+    This class's subclasses allow different types of callbacks to be added and
+    removed to them.
+    Registering a callback is done either by ``register_callback``, or by
+    defining a ``<type>_callback`` method.
+
+    Subclasses should define the `callback_types` attribute as a tuple of
+    allowed callback types.
     """
 
     finalize_early = False
@@ -414,6 +425,8 @@ class Command(HasParam):
     msg_summary = None
     msg_truncated = _('Results are truncated, try a more specific search')
 
+    callback_types = ()
+
     def __call__(self, *args, **options):
         """
         Perform validation and then execute the command.
@@ -1088,6 +1101,46 @@ class Command(HasParam):
 
         return json_dict
 
+    @classmethod
+    def get_callbacks(cls, callback_type):
+        """Yield callbacks of the given type"""
+        # Use one shared callback registry, keyed on class, to avoid problems
+        # with missing attributes being looked up in superclasses
+        callbacks = _callback_registry.get(callback_type, {}).get(cls, [None])
+        for callback in callbacks:
+            if callback is None:
+                try:
+                    yield getattr(cls, '%s_callback' % callback_type)
+                except AttributeError:
+                    pass
+            else:
+                yield callback
+
+    @classmethod
+    def register_callback(cls, callback_type, callback, first=False):
+        """Register a callback
+
+        :param callback_type: The callback type (e.g. 'pre', 'post')
+        :param callback: The callable added
+        :param first: If true, the new callback will be added before all
+            existing callbacks; otherwise it's added after them
+
+        Note that callbacks registered this way will be attached to this class
+        only, not to its subclasses.
+        """
+        assert callback_type in cls.callback_types
+        assert callable(callback)
+        _callback_registry.setdefault(callback_type, {})
+        try:
+            callbacks = _callback_registry[callback_type][cls]
+        except KeyError:
+            callbacks = _callback_registry[callback_type][cls] = [None]
+        if first:
+            callbacks.insert(0, callback)
+        else:
+            callbacks.append(callback)
+
+
 class LocalOrRemote(Command):
     """
     A command that is explicitly executed locally or remotely.

ipalib/plugins/baseldap.py

@@ -28,7 +28,7 @@ import base64
 import six
 
 from ipalib import api, crud, errors
-from ipalib import Method, Object, Command
+from ipalib import Method, Object
 from ipalib import Flag, Int, Str
 from ipalib.cli import to_cli
 from ipalib import output
@@ -865,59 +865,7 @@ def _check_limit_object_class(attributes, attrs, allow_only):
                 attribute=limitattrs[0]))
 
 
-class CallbackInterface(Method):
+class BaseLDAPCommand(Method):
-    """Callback registration interface
-
-    This class's subclasses allow different types of callbacks to be added and
-    removed to them.
-    Registering a callback is done either by ``register_callback``, or by
-    defining a ``<type>_callback`` method.
-
-    Subclasses should define the `_callback_registry` attribute as a dictionary
-    mapping allowed callback types to (initially) empty dictionaries.
-    """
-
-    _callback_registry = dict()
-
-    @classmethod
-    def get_callbacks(cls, callback_type):
-        """Yield callbacks of the given type"""
-        # Use one shared callback registry, keyed on class, to avoid problems
-        # with missing attributes being looked up in superclasses
-        callbacks = cls._callback_registry[callback_type].get(cls, [None])
-        for callback in callbacks:
-            if callback is None:
-                try:
-                    yield getattr(cls, '%s_callback' % callback_type)
-                except AttributeError:
-                    pass
-            else:
-                yield callback
-
-    @classmethod
-    def register_callback(cls, callback_type, callback, first=False):
-        """Register a callback
-
-        :param callback_type: The callback type (e.g. 'pre', 'post')
-        :param callback: The callable added
-        :param first: If true, the new callback will be added before all
-            existing callbacks; otherwise it's added after them
-
-        Note that callbacks registered this way will be attached to this class
-        only, not to its subclasses.
-        """
-        assert callable(callback)
-        try:
-            callbacks = cls._callback_registry[callback_type][cls]
-        except KeyError:
-            callbacks = cls._callback_registry[callback_type][cls] = [None]
-        if first:
-            callbacks.insert(0, callback)
-        else:
-            callbacks.append(callback)
-
-
-class BaseLDAPCommand(CallbackInterface, Command):
     """
     Base class for Base LDAP Commands.
     """
@@ -940,7 +888,10 @@ last, after all sets and adds."""),
                          exclude='webui',
                         )
 
-    _callback_registry = dict(pre={}, post={}, exc={}, interactive_prompt={})
+    callback_types = Method.callback_types + ('pre',
+                                              'post',
+                                              'exc',
+                                              'interactive_prompt')
 
     def get_summary_default(self, output):
         if 'value' in output:

ipatests/test_xmlrpc/test_baseldap_plugin.py

@@ -26,6 +26,7 @@ import ldap
 from ipapython.dn import DN
 from ipapython import ipaldap
 from ipalib import errors
+from ipalib.frontend import Command
 from ipalib.plugins import baseldap
 from ipatests.util import assert_deepequal
 import pytest
@@ -33,7 +34,7 @@ import pytest
 
 @pytest.mark.tier0
 def test_exc_wrapper():
-    """Test the CallbackInterface._exc_wrapper helper method"""
+    """Test the BaseLDAPCommand._exc_wrapper helper method"""
     handled_exceptions = []
 
     class test_callback(baseldap.BaseLDAPCommand):
@@ -77,8 +78,8 @@ def test_exc_wrapper():
 
 @pytest.mark.tier0
 def test_callback_registration():
-    class callbacktest_base(baseldap.CallbackInterface):
+    class callbacktest_base(Command):
-        _callback_registry = dict(test={})
+        callback_types = Command.callback_types + ('test',)
 
         def test_callback(self, param):
             messages.append(('Base test_callback', param))