Add exception_view_config decorator.

2 files changed, 95 insertions, 2 deletions

diff --git a/pyramid/tests/test_view.py b/pyramid/tests/test_view.py
index 2de44d579..d18c6eca4 100644
--- a/pyramid/tests/test_view.py
+++ b/pyramid/tests/test_view.py
@@ -132,7 +132,49 @@ class Test_forbidden_view_config(BaseTest, unittest.TestCase):
         self.assertEqual(settings[0]['view'], None) # comes from call_venusian
         self.assertEqual(settings[0]['attr'], 'view')
         self.assertEqual(settings[0]['_info'], 'codeinfo')
-        
+
+class Test_exception_view_config(BaseTest, unittest.TestCase):
+    def _makeOne(self, **kw):
+        from pyramid.view import exception_view_config
+        return exception_view_config(**kw)
+
+    def test_ctor(self):
+        inst = self._makeOne(context=Exception, path_info='path_info')
+        self.assertEqual(inst.__dict__,
+                         {'context':Exception, 'path_info':'path_info'})
+
+    def test_it_function(self):
+        def view(request): pass
+        decorator = self._makeOne(context=Exception, renderer='renderer')
+        venusian = DummyVenusian()
+        decorator.venusian = venusian
+        wrapped = decorator(view)
+        self.assertTrue(wrapped is view)
+        config = call_venusian(venusian)
+        settings = config.settings
+        self.assertEqual(
+            settings,
+            [{'venusian': venusian, 'context': Exception,
+              'renderer': 'renderer', '_info': 'codeinfo', 'view': None}]
+            )
+
+    def test_it_class(self):
+        decorator = self._makeOne()
+        venusian = DummyVenusian()
+        decorator.venusian = venusian
+        decorator.venusian.info.scope = 'class'
+        class view(object): pass
+        wrapped = decorator(view)
+        self.assertTrue(wrapped is view)
+        config = call_venusian(venusian)
+        settings = config.settings
+        self.assertEqual(len(settings), 1)
+        self.assertEqual(len(settings[0]), 4)
+        self.assertEqual(settings[0]['venusian'], venusian)
+        self.assertEqual(settings[0]['view'], None) # comes from call_venusian
+        self.assertEqual(settings[0]['attr'], 'view')
+        self.assertEqual(settings[0]['_info'], 'codeinfo')
+
 class RenderViewToResponseTests(BaseTest, unittest.TestCase):
     def _callFUT(self, *arg, **kw):
         from pyramid.view import render_view_to_response
@@ -898,7 +940,7 @@ class DummyConfig(object):
     def add_view(self, **kw):
         self.settings.append(kw)
 
-    add_notfound_view = add_forbidden_view = add_view
+    add_notfound_view = add_forbidden_view = add_exception_view = add_view
 
     def with_package(self, pkg):
         self.pkg = pkg
diff --git a/pyramid/view.py b/pyramid/view.py
index 88c6397af..5a9f2a068 100644
--- a/pyramid/view.py
+++ b/pyramid/view.py
@@ -463,6 +463,57 @@ class forbidden_view_config(object):
         settings['_info'] = info.codeinfo # fbo "action_method"
         return wrapped
 
+class exception_view_config(object):
+    """
+    .. versionadded:: 1.8
+
+    An analogue of :class:`pyramid.view.view_config` which registers an
+    exception view.
+
+    The exception_view_config constructor requires an exception context, and
+    additionally accepts most of the same argumenta as the constructor of
+    :class:`pyramid.view.view_config`.  It can be used in the same places,
+    and behaves in largely the same way, except it always registers an exception
+    view instead of a 'normal' view.
+
+    Example:
+
+    .. code-block:: python
+
+        from pyramid.view import exception_view_config
+        from pyramid.response import Response
+
+        @exception_view_config(context=ValueError)
+        def error_view(request):
+            return Response('A value error ocurred')
+
+    All arguments passed to this function have the same meaning as
+    :meth:`pyramid.view.view_config` and each predicate argument restricts
+    the set of circumstances under which this exception view will be invoked.
+    """
+
+    def __init__(self, **settings):
+        self.__dict__.update(settings)
+
+    def __call__(self, wrapped):
+        settings = self.__dict__.copy()
+
+        def callback(context, name, ob):
+            config = context.config.with_package(info.module)
+            config.add_exception_view(view=ob, **settings)
+
+        info = self.venusian.attach(wrapped, callback, category='pyramid')
+
+        if info.scope == 'class':
+            # if the decorator was attached to a method in a class, or
+            # otherwise executed at class scope, we need to set an
+            # 'attr' into the settings if one isn't already in there
+            if settings.get('attr') is None:
+                settings['attr'] = wrapped.__name__
+
+        settings['_info'] = info.codeinfo # fbo "action_method"
+        return wrapped
+
 def _find_views(
     registry,
     request_iface,