A `web framework <http://pylonsproject.org>`_.
A bit of code that sits between the Pyramid router's main request
handling function and the upstream WSGI component that uses Pyramid as
its 'app'. The word "tween" is a contraction of "between". A tween may
be used by Pyramid framework extensions, to provide, for example,
Pyramid-specific view timing support, bookkeeping code that examines
exceptions before they are returned to the upstream WSGI application, or
a variety of other features. Tweens behave a bit like WSGI 'middleware'
but they have the benefit of running in a context in which they have
access to the Pyramid application registry as well as the Pyramid
rendering machinery. See the main Pyramid documentation for more
information about tweens.
An exception view is a :Pyramid view callable which may be invoked when
an exception is raised during request processing.