Allow using apphook_pool.register() as a decorator.

If it returns None, then the value of the defined class will be None,
which makes it dfficult to access the class!

It can still be used in the old way. The lambda is only necessary when
register is invoked with arguments, for example:

    @apphook_pool.register(discovering_apps=True)
    class MyApp(CMSApp): ...

and I don't know if that should be allowed or not.

cms/apphook_pool.py

@@ -22,9 +22,13 @@ def clear(self):
         self.apps = {}
         self.discovered = False
 
-    def register(self, app, discovering_apps=False):
+    def register(self, app=None, discovering_apps=False):
+        # allow use as a decorator
+        if app is None:
+            return lambda app: self.register(app, discovering_apps)
+
         if self.apphooks and not discovering_apps:
-            return
+            return app
 
         if app.__name__ in self.apps:
             raise AppAlreadyRegistered(
@@ -40,6 +44,7 @@ def register(self, app, discovering_apps=False):
                 "but the 'menus' attribute is empty, did you make a typo?" % app.__name__)
 
         self.apps[app.__name__] = app
+        return app
 
     def discover_apps(self):
         self.apphooks = get_cms_setting('APPHOOKS')

cms/tests/apphooks.py

@@ -6,6 +6,7 @@
 from django.core.urlresolvers import clear_url_caches, reverse
 
 from cms.api import create_page, create_title
+from cms.app_base import CMSApp
 from cms.apphook_pool import apphook_pool
 from cms.appresolver import applications_page_check, clear_app_resolvers, get_app_patterns
 from cms.models import Title
@@ -444,6 +445,20 @@ def test_multiple_apphooks(self):
 
             apphook_pool.clear()
 
+    def test_apphook_pool_register_returns_apphook(self):
+        @apphook_pool.register
+        class TestApp(CMSApp):
+            name = "Test App"
+        self.assertIsNotNone(TestApp)
+
+        # Now test the quick return codepath, when apphooks is not empty
+        apphook_pool.apphooks.append("foo")
+
+        @apphook_pool.register
+        class TestApp2(CMSApp):
+            name = "Test App 2"
+        self.assertIsNotNone(TestApp2)
+
 
 class ApphooksPageLanguageUrlTestCase(SettingsOverrideTestCase):
     settings_overrides = {'ROOT_URLCONF': 'cms.test_utils.project.second_urls_for_apphook_tests'}