On Sun, Oct 3, 2010 at 11:20 AM, Russell Keith-Magee <russ...@keith-magee.com> wrote: >> The issue is not only the frequency of failure, but how explicit/clear >> it is. The failure here is so obscure and difficult to track down, it >> is likely to generate an outsize support burden. In contrast, raising >> an error on assigning to self can be completely explicit; no hours of >> painful and confusing debugging necessary. >> >> Let's also be clear to distinguish "just document that you don't store >> state on self" vs "raise an error if you set an attribute on self." >> These are proposals with very different characteristics in terms of >> likely confusion and support burden. > > Agreed. The "just document" approach is a non-starter; the 'error when > you set attribute on self' is at least a technically viable option. > > My problem with the error-based approach is entirely conceptual -- it > feels to me like throwing the baby out with the bathwater. I'm having > a lot of trouble with the idea that class instances have state in > every other Python class instance, and if we introduce an API that > physically prohibits instance state that -- no matter how good the > technical reasoning -- we're going to: > > * Cause confusion amongst new users as to why this seemingly obvious > thing can't be done > > * Ignore the legitimate occasions where using state is a useful > architectural approach.
While I'm in the "one singleton view instance is best" camp and think that storing some state on the request and some on the view is a bit gross, I understand Russell's arguments. New users are simply going to save stuff on self no matter how much we complain, document etc. It's simply a reality that likely can't be helped much. Other frameworks seem have View/Handler instances per request, such as appengine's webapp so there is some precedent for creating an instance per request. http://code.google.com/appengine/docs/python/gettingstarted/handlingforms.html Flask seems to do it the callable singleton way: http://flask.pocoo.org/docs/patterns/lazyloading/ Is there any precedent in other frameworks for doing it the singleton way? Talking a bit about how other frameworks/libraries do this might be a good idea to figure out what Joe User is likely to do. -- Ian http://www.ianlewis.org/ -- You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-develop...@googlegroups.com. To unsubscribe from this group, send email to django-developers+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-developers?hl=en.
