Source code for pyramid.tweens

import sys

from pyramid.compat import reraise
from pyramid.exceptions import PredicateMismatch
from pyramid.interfaces import (

from zope.interface import providedBy
from pyramid.view import _call_view

[docs]def excview_tween_factory(handler, registry): """ A :term:`tween` factory which produces a tween that catches an exception raised by downstream tweens (or the main Pyramid request handler) and, if possible, converts it into a Response using an :term:`exception view`.""" def excview_tween(request): attrs = request.__dict__ try: response = handler(request) except Exception as exc: # WARNING: do not assign the result of sys.exc_info() to a local # var here, doing so will cause a leak. We used to actually # explicitly delete both "exception" and "exc_info" from ``attrs`` # in a ``finally:`` clause below, but now we do not because these # attributes are useful to upstream tweens. This actually still # apparently causes a reference cycle, but it is broken # successfully by the garbage collector (see # attrs['exc_info'] = sys.exc_info() attrs['exception'] = exc # clear old generated request.response, if any; it may # have been mutated by the view, and its state is not # sane (e.g. caching headers) if 'response' in attrs: del attrs['response'] # we use .get instead of .__getitem__ below due to # request_iface = attrs.get('request_iface', IRequest) provides = providedBy(exc) try: response = _call_view( registry, request, exc, provides, '', view_classifier=IExceptionViewClassifier, request_iface=request_iface.combined ) # if views matched but did not pass predicates, squash the error # and re-raise the original exception except PredicateMismatch: response = None # re-raise the original exception as no exception views were # able to handle the error if response is None: reraise(*attrs['exc_info']) return response return excview_tween
MAIN = 'MAIN' INGRESS = 'INGRESS' EXCVIEW = 'pyramid.tweens.excview_tween_factory'