From b4c212546023e41243ea30886f9afb8625e89c93 Mon Sep 17 00:00:00 2001 From: Chris McDonough Date: Wed, 21 Jul 2010 01:58:48 +0000 Subject: - A new internal exception class (*not* an API) named ``repoze.bfg.exceptions.PredicateMismatch`` now exists. This exception is currently raised when no constituent view of a multiview can be called (due to no predicate match). Previously, in this situation, a ``repoze.bfg.exceptions.NotFound`` was raised. We provide backwards compatibility for code that expected a ``NotFound`` to be raised when no predicates match by causing ``repoze.bfg.exceptions.PredicateMismatch`` to inherit from ``NotFound``. This will cause any exception view registered for ``NotFound`` to be called when a predicate mismatch occurs, as was the previous behavior. There is however, one perverse case that will expose a backwards incompatibility. If 1) you had a view that was registered as a member of a multiview 2) this view explicitly raised a ``NotFound`` exception *in order to* proceed to the next predicate check in the multiview, that code will now behave differently: rather than skipping to the next view match, a NotFound will be raised to the top-level exception handling machinery instead. For code to be depending upon the behavior of a view raising ``NotFound`` to proceed to the next predicate match, would be tragic, but not impossible, given that ``NotFound`` is a public interface. ``repoze.bfg.exceptions.PredicateMismatch`` is not a public API and cannot be depended upon by application code, so you should not change your view code to raise ``PredicateMismatch``. Instead, move the logic which raised the ``NotFound`` exception in the view out into a custom view predicate. --- repoze/bfg/exceptions.py | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'repoze/bfg/exceptions.py') diff --git a/repoze/bfg/exceptions.py b/repoze/bfg/exceptions.py index b0922c1e3..00cb76883 100644 --- a/repoze/bfg/exceptions.py +++ b/repoze/bfg/exceptions.py @@ -40,3 +40,11 @@ class URLDecodeError(UnicodeDecodeError): class ConfigurationError(ZCE): """ Raised when inappropriate input values are supplied to an API method of a :term:`Configurator`""" + +class PredicateMismatch(NotFound): + """ Internal exception (not an API) raised by multiviews when no + view matches. This exception subclasses the ``NotFound`` + exception only one reason: if it reaches the main exception + handler, it should be treated like a ``NotFound`` by any exception + view registrations.""" + -- cgit v1.2.3