Remove "contributes_to" decorator and supporting code (#402)

* CLN : Remove contributes_to decorator

and supporting code, tests

	modified:   envisage/api.py
	modified:   envisage/extension_point.py
	modified:   envisage/plugin.py
	modified:   envisage/tests/test_plugin.py

* FIX : flake8 - unused import

	modified:   envisage/plugin.py

* FIX : Specifically handle case where there are no traits that contribute

to the extension point
otherwise, it just goes into the else clause which raises an error

	modified:   envisage/plugin.py

envisage/api.py

@@ -31,7 +31,6 @@
 - :class:`~.CorePlugin`
 - :class:`~.EggPluginManager`
 - :class:`~.ExtensionPoint`
-- :func:`~.contributes_to`
 - :class:`~.ExtensionPointBinding`
 - :func:`~.bind_extension_point`
 - :class:`~.ExtensionProvider`
@@ -70,7 +69,7 @@
 from .core_plugin import CorePlugin
 from .egg_plugin_manager import EggPluginManager
 from .extension_registry import ExtensionRegistry
-from .extension_point import ExtensionPoint, contributes_to
+from .extension_point import ExtensionPoint
 from .extension_point_binding import (
     ExtensionPointBinding,
     bind_extension_point,

envisage/extension_point.py

@@ -24,47 +24,6 @@
 from .i_extension_point import IExtensionPoint
 
 
-def contributes_to(id):
-    """ A factory for extension point decorators!
-
-    As an alternative to making contributions via traits, you can use this
-    decorator to mark any method on a 'Plugin' as contributing to an extension
-    point (note this is *only* used on 'Plugin' instances!).
-
-    e.g. Using a trait you might have something like::
-
-        class MyPlugin(Plugin):
-            messages = List(contributes_to='acme.messages')
-
-            def _messages_default(self):
-                return ['Hello', 'Hola']
-
-    whereas, using the decorator, it would be::
-
-        class MyPlugin(Plugin):
-            @contributes_to('acme.messages')
-            def _get_messages(self):
-                return ['Hello', 'Hola']
-
-    There is not much in it really, but the decorator version looks a little
-    less like 'magic' since it doesn't require the developer to know about
-    Traits default initializers. However, if you know that you will want to
-    dynamically change your contributions then use the trait version  because
-    all you have to do is change the value of the trait and the framework will
-    react accordingly.
-
-    """
-
-    def decorator(fn):
-        """ A decorator for marking methods as extension contributors. """
-
-        fn.__extension_point__ = id
-
-        return fn
-
-    return decorator
-
-
 # Exception message template.
 INVALID_TRAIT_TYPE = (
     'extension points must be "List"s e.g. List, List(Int)'

envisage/plugin.py

@@ -10,7 +10,6 @@
 """ The default implementation of the 'IPlugin' interface. """
 
 # Standard library imports.
-import inspect
 import logging
 import os
 from os.path import exists, join
@@ -131,26 +130,8 @@ def get_extensions(self, extension_point_id):
         # fine to allow mutiple traits!
         trait_names = self.trait_names(contributes_to=extension_point_id)
 
-        # FIXME: This is a temporary fix, which was necessary due to the
-        #        namespace refactor, but should be removed at some point.
         if len(trait_names) == 0:
-            old_id = "enthought." + extension_point_id
-            trait_names = self.trait_names(contributes_to=old_id)
-        #            if trait_names:
-        #                print 'deprecated:', old_id
-
-        if len(trait_names) == 0:
-            # If there is no contributing trait then look for any decorated
-            # methods.
-            extensions = self._harvest_methods(extension_point_id)
-
-            # FIXME: This is a temporary fix, which was necessary due to the
-            #        namespace refactor, but should be removed at some point.
-            if not extensions:
-                old_id = "enthought." + extension_point_id
-                extensions = self._harvest_methods(old_id)
-        #                if extensions:
-        #                    print 'deprecated:', old_id
+            extensions = []
 
         elif len(trait_names) == 1:
             extensions = self._get_extensions_from_trait(trait_names[0])
@@ -372,47 +353,6 @@ def _get_service_protocol(self, trait):
 
         return protocol
 
-    def _harvest_methods(self, extension_point_id):
-        """ Harvest all method-based contributions. """
-
-        extensions = []
-        # Using inspect.getmembers(self) here will cause an infinite recursion,
-        # so use an internal HasTraits method for inspecting the MRO of the
-        # instance's type to find all methods instead.
-        for name in self._each_trait_method(self):
-            value = getattr(self, name)
-            if self._is_extension_method(value, extension_point_id):
-                result = value()
-                if not isinstance(result, list):
-                    result = [result]
-
-                extensions.extend(result)
-
-        return extensions
-
-    def _is_extension_method(self, value, extension_point_id):
-        """ Return True if the value is an extension method.
-
-        i.e. If the method is one that makes a contribution to the extension
-        point. Currently there is exactly one way to make a method make a
-        contribution, and that is to mark it using the 'contributes_to'
-        decorator, e.g::
-
-          @contributes_to('acme.motd.messages')
-          def get_messages(self):
-              ...
-              messages = [...]
-              ...
-              return messages
-
-        """
-
-        is_extension_method = inspect.ismethod(
-            value
-        ) and extension_point_id == getattr(value, "__extension_point__", None)
-
-        return is_extension_method
-
     def _register_service_factory(self, trait_name, trait):
         """ Register a service factory for the specified trait. """
 

envisage/tests/test_plugin.py

@@ -16,7 +16,7 @@
 
 # Enthought library imports.
 from envisage.api import Application, ExtensionPoint
-from envisage.api import IPluginActivator, Plugin, contributes_to
+from envisage.api import IPluginActivator, Plugin
 from envisage.tests.ets_config_patcher import ETSConfigPatcher
 from traits.api import HasTraits, Instance, Int, Interface, List
 from traits.api import provides
@@ -260,47 +260,6 @@ class PluginB(Plugin):
         # contributing to the same extension point.
         self.assertEqual([1, 2, 3], application.get_extensions("x"))
 
-    def test_contributes_to_decorator(self):
-        """ contributes to decorator """
-
-        class PluginA(Plugin):
-            id = "A"
-            x = ExtensionPoint(List, id="x")
-
-        class PluginB(Plugin):
-            id = "B"
-
-            @contributes_to("x")
-            def _x_contributions(self):
-                return [1, 2, 3]
-
-        a = PluginA()
-        b = PluginB()
-
-        application = TestApplication(plugins=[a, b])
-        self.assertEqual([1, 2, 3], application.get_extensions("x"))
-
-    def test_contributes_to_decorator_ignored_if_trait_present(self):
-        """ contributes to decorator ignored if trait present """
-
-        class PluginA(Plugin):
-            id = "A"
-            x = ExtensionPoint(List, id="x")
-
-        class PluginB(Plugin):
-            id = "B"
-            x = List([1, 2, 3], contributes_to="x")
-
-            @contributes_to("x")
-            def _x_contributions(self):
-                return [4, 5, 6]
-
-        a = PluginA()
-        b = PluginB()
-
-        application = TestApplication(plugins=[a, b])
-        self.assertEqual([1, 2, 3], application.get_extensions("x"))
-
     def test_add_plugins_to_empty_application(self):
         """ add plugins to empty application """