Major Description
In current version of mod_python req.filename is writable, but
req.path_info isn't.
If req.path_info were writable it would more easily allow a middleware
stack to be implemented in mod_python. This is because a middleware
component could modify req.path_info as necessary as the path info is
progressively processed. This would be better than a middleware
component having to create a parallel request attribute just for this
purpose as by being able to change req.path_info existing handlers such
as mod_python.publisher which already look at req.filename and
req.path_info could still be utilised in various ways within the
middleware stack. Same for any handlers which third parties may have
developed. Thus would eliminate the need to copy existing handlers and
modify them to get them to work, a middleware component would simply
need to setup req.filename and req.path_info as appropriate and the
existing handlers would work unmodified.