Added inheritance for hooks from parent classes

also added hook inheritance from mixins, and adding
hooks to child controllers, added as sub-controllers.

Fixes bug 1330673

Change-Id: I709cece7bcce26943b254b15dc8ddac5613b1202

3 files changed, 182 insertions, 4 deletions

diff --git a/docs/source/hooks.rst b/docs/source/hooks.rst
index 7796189..18a530f 100644
--- a/docs/source/hooks.rst
+++ b/docs/source/hooks.rst
@@ -130,9 +130,106 @@ when we run the app and browse the application from our web browser.
 
     about to enter the controller...
     DO SOMETHING!
-    method: 	 GET
-    response: 	 200 OK
+    method:      GET
+    response:    200 OK
 
+Hooks can be inherited from parent class or mixins. Just make sure to
+subclass from :class:`~pecan.hooks.HookController`.
+
+::
+
+    from pecan import expose
+    from pecan.hooks import PecanHook, HookController
+
+    class ParentHook(PecanHook):
+
+        priority = 1
+
+        def before(self, state):
+            print "\nabout to enter the parent controller..."
+
+    class CommonHook(PecanHook):
+
+        priority = 2
+
+        def before(self, state):
+            print "\njust a common hook..."
+
+    class SubHook(PecanHook):
+
+        def before(self, state):
+            print "\nabout to enter the subcontroller..."
+
+    class SubMixin(object):
+        __hooks__ = [SubHook()]
+
+    # We'll use the same instance for both controllers,
+    # to avoid double calls
+    common = CommonHook()
+
+    class SubController(HookController, SubMixin):
+
+        __hooks__ = [common]
+
+        @expose('json')
+        def index(self):
+            print "\nI AM THE SUB!"
+            return dict()
+
+    class RootController(HookController):
+
+        __hooks__ = [common, ParentHook()]
+
+        @expose('json')
+        def index(self):
+            print "\nI AM THE ROOT!"
+            return dict()
+
+        sub = SubController()
+
+Let's see what happens when we run the app.
+First loading the root controller:
+
+::
+
+    pecan serve config.py
+    serving on 0.0.0.0:8080 view at http://127.0.0.1:8080
+
+    GET / HTTP/1.1" 200
+
+    about to enter the parent controller...
+
+    just a common hook
+
+    I AM THE ROOT!
+
+Then loading the sub controller:
+
+::
+
+    pecan serve config.py
+    serving on 0.0.0.0:8080 view at http://127.0.0.1:8080
+
+    GET /sub HTTP/1.1" 200
+
+    about to enter the parent controller...
+
+    just a common hook
+
+    about to enter the subcontroller...
+
+    I AM THE SUB!
+
+.. note::
+
+    Make sure to set proper priority values for nested hooks in order
+    to get them executed in the desired order.
+
+.. warning::
+
+    Two hooks of the same type will be added/executed twice, if passed as
+    different instances to a parent and a child controller.
+    If passed as one instance variable - will be invoked once for both controllers.
 
 Hooks That Come with Pecan
 --------------------------
diff --git a/pecan/hooks.py b/pecan/hooks.py
index 4ceeb42..27dc872 100644
--- a/pecan/hooks.py
+++ b/pecan/hooks.py
@@ -14,6 +14,10 @@ __all__ = [
 
 def walk_controller(root_class, controller, hooks):
     if not isinstance(controller, (int, dict)):
+        for hook in getattr(controller, '__hooks__', []):
+            # Append hooks from controller class definition
+            hooks.add(hook)
+
         for name, value in getmembers(controller):
             if name == 'controller':
                 continue
@@ -22,7 +26,7 @@ def walk_controller(root_class, controller, hooks):
 
             if iscontroller(value):
                 for hook in hooks:
-                    value._pecan.setdefault('hooks', []).append(hook)
+                    value._pecan.setdefault('hooks', set()).add(hook)
             elif hasattr(value, '__class__'):
                 if name.startswith('__') and name.endswith('__'):
                     continue
@@ -37,7 +41,12 @@ class HookControllerMeta(type):
     '''
 
     def __init__(cls, name, bases, dict_):
-        walk_controller(cls, cls, dict_.get('__hooks__', []))
+        hooks = set(dict_.get('__hooks__', []))
+        for base in bases:
+            # Add hooks from parent class and mixins
+            for hook in getattr(base, '__hooks__', []):
+                hooks.add(hook)
+        walk_controller(cls, cls, hooks)
 
 
 HookController = HookControllerMeta(
diff --git a/pecan/tests/test_hooks.py b/pecan/tests/test_hooks.py
index 44963bf..8f1ca39 100644
--- a/pecan/tests/test_hooks.py
+++ b/pecan/tests/test_hooks.py
@@ -339,6 +339,78 @@ class TestHooks(PecanTestCase):
         assert run_hook[4] == 'after1'
         assert run_hook[5] == 'after2'
 
+    def test_mixin_hooks(self):
+        run_hook = []
+
+        class HelperHook(PecanHook):
+            priority = 2
+
+            def before(self, state):
+                run_hook.append('helper - before hook')
+
+        # we'll use the same hook instance to avoid duplicate calls
+        helper_hook = HelperHook()
+
+        class LastHook(PecanHook):
+            priority = 200
+
+            def before(self, state):
+                run_hook.append('last - before hook')
+
+        class SimpleHook(PecanHook):
+            priority = 1
+
+            def before(self, state):
+                run_hook.append('simple - before hook')
+
+        class HelperMixin(object):
+            __hooks__ = [helper_hook]
+
+        class LastMixin(object):
+            __hooks__ = [LastHook()]
+
+        class SubController(HookController, HelperMixin):
+            __hooks__ = [LastHook()]
+
+            @expose()
+            def index(self):
+                return "This is sub controller!"
+
+        class RootController(HookController, LastMixin):
+            __hooks__ = [SimpleHook(), helper_hook]
+
+            @expose()
+            def index(self):
+                run_hook.append('inside')
+                return 'Hello, World!'
+
+            sub = SubController()
+
+        papp = make_app(RootController())
+        app = TestApp(papp)
+        response = app.get('/')
+        assert response.status_int == 200
+        assert response.body == b_('Hello, World!')
+
+        assert len(run_hook) == 4
+        assert run_hook[0] == 'simple - before hook', run_hook[0]
+        assert run_hook[1] == 'helper - before hook', run_hook[1]
+        assert run_hook[2] == 'last - before hook', run_hook[2]
+        assert run_hook[3] == 'inside', run_hook[3]
+
+        run_hook = []
+        response = app.get('/sub/')
+        assert response.status_int == 200
+        assert response.body == b_('This is sub controller!')
+
+        assert len(run_hook) == 4, run_hook
+        assert run_hook[0] == 'simple - before hook', run_hook[0]
+        assert run_hook[1] == 'helper - before hook', run_hook[1]
+        assert run_hook[2] == 'last - before hook', run_hook[2]
+        # LastHook is invoked once again -
+        # for each different instance of the Hook in the two Controllers
+        assert run_hook[3] == 'last - before hook', run_hook[3]
+
 
 class TestTransactionHook(PecanTestCase):
     def test_transaction_hook(self):