[patch] Add extension point for Session modification

[Morris]

I realize that the IUserdirectory functionality currently scheduled for 0.12 will (and should) in all likelihood supercede this ...but I need it now.

This patch adds a new extension point in trac/web/main.py called ISessionObserver. Calls to _get_session (performed as part of every request dispatch) will call pass_user_fields(username, email, name) on every component that implements ISessionObserver; the required return is a tuple of the form (newemail, newname). If the returned values are non-None and different from the original values, the main Session dict is updated before being returned.

What is this good for? If you've ever wanted to autopopulate-at-login your user's display names and/or email addresses, then here you go. Apply this patch, then write a plugin that implements ISessionObserver and does your user data lookup in the pass_user_fields method. If this means hitting a DB, I'd strongly recommend adding some simple caching to your plugin to reduce the flurry of DB hits that this feature would cause :)

NOTE: you'll probably only want to implement ISessionObserver in one plugin -- having multiple ISessionObserver components will behave in undefined ways since there's no way (to my knowledge) to guarantee the order in which they'll be called.

[Morris]

patch to add ISessionObserver to trac/web/main.py (against 0.11 dev/trunk)

[osimons]

I'm just setting this to 0.12 to get it on the radar along with the other user-related feature requests that may be handled there.