On 04/04/2012 05:43 PM, Ethan Jucovy wrote:
[
http://svn.apache.org/viewvc/incubator/bloodhound/trunk/trac/trac/core.py?view=diff&r1=1309469&r2=1309470&pathrev=1309470
r1309470] fixes by dynamically replacing the __init__ of components with
one that runs the original __init__ on the condition that it has not
already been run.
I suspect what would be better in the long run would be to catch the
recursion error and turn it into something that can be reported but allows
Bloodhound to continue working. Plugins should probably keep track of
whether an instance has already been initialised.
This issue was raised on trac-dev[1]. It was pointed out that the
ThemeEngine plugin is incorrectly accessing its extension points in
__init__, which it should not do:
"A component constructor is called in a
special way, as you've found out, and it should really do pretty
much nothing. Example of valid use is to set a list to [], a
hash to {}, or such. In trunk you could even use @lazy
(http://trac.edgewall.org/changeset/10737) to help with such
things. So doing anything lengthy is prohibited and the same
for "re-entering" the component machinery."
Perhaps Trac core should be throwing a more helpful error than infinite
recursion, but the correct fix here is to make ThemeEngineSystem.__init__
do less (e.g. ``self._info = None``) and populate its ``self.info`` dict
lazily. There's no need for this __init__-replacing magic in core.
[1]
http://old.nabble.com/Create-new-ticket-vs-reopen--9418-(if-necessary--)-td33164546.html
Ah, thanks for pointing that out. I was about to write a ticket to get
someone to get the theme engine to change the implementation.
I don't particularly mind that a plugin wants to do a lot in their
__init__ as long as they are prepared to deal with the potential error.
As I think I already say, the only fault I see in Trac on this issue is
that it doesn't deal with it quite helpfully enough. Basically I think
it should survive the event to the extent of allowing the admin to
disable the offending plugin from the admin interface.
Cheers,
Gary
