Merge branch 'feature.callable-acl'

4 files changed, 51 insertions, 5 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 85dd3be2a..ae2cafba4 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,3 +1,16 @@
+next release
+============
+
+Features
+--------
+
+- ``ACLAuthorizationPolicy`` supports ``__acl__`` as a callable. This
+  removes the ambiguity between the potential ``AttributeError`` that would
+  be raised on the ``context`` when the property was not defined and the
+  ``AttributeError`` that could be raised from any user-defined code within
+  a dynamic property. It is recommended to define a dynamic ACL as a callable
+  to avoid this ambiguity. See https://github.com/Pylons/pyramid/issues/735.
+
 1.4 (2012-12-18)
 ================
 
diff --git a/docs/narr/security.rst b/docs/narr/security.rst
index 5b79edd19..203aa2404 100644
--- a/docs/narr/security.rst
+++ b/docs/narr/security.rst
@@ -234,8 +234,8 @@ class:
 .. code-block:: python
    :linenos:
 
-   from pyramid.security import Everyone
    from pyramid.security import Allow
+   from pyramid.security import Everyone
 
    class Blog(object):
        __acl__ = [
@@ -250,8 +250,8 @@ Or, if your resources are persistent, an ACL might be specified via the
 .. code-block:: python
    :linenos:
 
-   from pyramid.security import Everyone
    from pyramid.security import Allow
+   from pyramid.security import Everyone
 
    class Blog(object):
        pass
@@ -270,6 +270,27 @@ resource instances with an ACL (as opposed to just decorating their class) in
 applications such as "CMS" systems where fine-grained access is required on
 an object-by-object basis.
 
+Dynamic ACLs are also possible by turning the ACL into a callable on the
+resource. This may allow the ACL to dynamically generate rules based on
+properties of the instance.
+
+.. code-block:: python
+   :linenos:
+
+   from pyramid.security import Allow
+   from pyramid.security import Everyone
+
+   class Blog(object):
+       def __acl__(self):
+           return [
+               (Allow, Everyone, 'view'),
+               (Allow, self.owner, 'edit'),
+               (Allow, 'group:editors', 'edit'),
+           ]
+
+       def __init__(self, owner):
+           self.owner = owner
+
 .. index::
    single: ACE
    single: access control entry
@@ -282,8 +303,8 @@ Here's an example ACL:
 .. code-block:: python
    :linenos:
 
-   from pyramid.security import Everyone
    from pyramid.security import Allow
+   from pyramid.security import Everyone
 
    __acl__ = [
            (Allow, Everyone, 'view'),
@@ -321,9 +342,9 @@ order dictated by the ACL*.  So if you have an ACL like this:
 .. code-block:: python
    :linenos:
 
-   from pyramid.security import Everyone
    from pyramid.security import Allow
    from pyramid.security import Deny
+   from pyramid.security import Everyone
 
    __acl__ = [
        (Allow, Everyone, 'view'),
@@ -359,8 +380,8 @@ ACE, as below.
 .. code-block:: python
    :linenos:
 
-   from pyramid.security import Everyone
    from pyramid.security import Allow
+   from pyramid.security import Everyone
 
    __acl__ = [
        (Allow, Everyone, 'view'),
diff --git a/pyramid/authorization.py b/pyramid/authorization.py
index 943f8bd00..1fd05e244 100644
--- a/pyramid/authorization.py
+++ b/pyramid/authorization.py
@@ -80,6 +80,9 @@ class ACLAuthorizationPolicy(object):
             except AttributeError:
                 continue
 
+            if acl and callable(acl):
+                acl = acl()
+
             for ace in acl:
                 ace_action, ace_principal, ace_permissions = ace
                 if ace_principal in principals:
diff --git a/pyramid/tests/test_authorization.py b/pyramid/tests/test_authorization.py
index 27f2a18b4..60b1b0c8d 100644
--- a/pyramid/tests/test_authorization.py
+++ b/pyramid/tests/test_authorization.py
@@ -215,6 +215,15 @@ class TestACLAuthorizationPolicy(unittest.TestCase):
         result = sorted(
             policy.principals_allowed_by_permission(context, 'read'))
         self.assertEqual(result, [])
+
+    def test_callable_acl(self):
+        from pyramid.security import Allow
+        context = DummyContext()
+        fn = lambda self: [(Allow, 'bob', 'read')]
+        context.__acl__ = fn.__get__(context, context.__class__)
+        policy = self._makeOne()
+        result = policy.permits(context, ['bob'], 'read')
+        self.assertTrue(result)
         
 
 class DummyContext: