[Zope-CMF] Odd behavior with lazy ActionInfo evaluation in CMF 1.5

[Alec Mitchell]

On Thursday 30 June 2005 09:11 am, Alec Mitchell wrote:
> Hello all,
>
> I've noticed something odd when viewing the Plone 2.1 (CMF-1.5 branch)
> front-page as Anonymous.  The 'user' action 'join' defined in
> portal_registration gives as it's url 'http://mysite/test_site/join_form',
> as expected.  The same action when retrieved again in 'portlet_login' gives
> 'http://mysite/test_site/<function _getURL at 0x40fa102c>', which is
> obviously a problem.
>
> I've done a little hand debugging to attempt to figure out how this
> happens, and have found the following:
>
> 1) On page view, 'global_defines.pt' is called from main_template and
> defines the 'action' structure using a call to
> portal_actions.listFilteredActionsFor(here).
> 2) This creates the lazily mapped ActionInfo object for the 'join' action
> from the 'join' ActionInformation object in portal_registration.  At this
> time actions['join']['url'] is set to self._getURL, and the key 'url' is
> added to the ActionInfo's 'lazy_keys' list.
> 3) This ActionInfo object, unchanged, is used in the path expression
> 'action/url' in the loop through user actions in 'global_personalbar.pt'
> which is called from main_template.
> 4) This causes ActionInfo.__getitem__ to be called for 'url' and the
> _getURL method is retrieved.  Because 'url' is in 'lazy_keys', the method
> is evaluated, the the ActionInfo dict is updated with the evaluated value
> for 'url', and the 'url' entry is removed from 'lazy_keys'.
>
> The above steps are the expected behavior, and appear to work perfectly. 
> The strange part follows:
>
> 5) 'portlet_login' gets the url for the action using "[a['url'] for a in
> actions['user'] if a['id']=='join']".
> 6) This results in another call to ActionInfo.__getitem__ on what should be
> the same ActionInfo instance.  Again the _getURL method is retrieved, which
> is unexpected as that value was replaced with the result of calling the
> method in step #4 above.  'lazy_keys' no longer has the entry 'url', so the
> method is not evaluated, and the method itself is returned.
>
> Though the ActionInfo for this action is only created once, and the changes
> made to it's 'lazy_keys' variable can be seen on subsequent calls to the
> instance, it appears that some of the changes to the object are getting
> lost between subsequent calls to __getitem__.  In fact, I tested setting a
> new instance variable during the __getitem__ call, and on the subsequent
> call this variable was no longer set!
>
> If these were persistent objects I would attribute this sort of weirdness
> to the need for some _p_changed updates or some partial transaction
> rollback, but these are simple UserDict subclasses which are never stored
> in the ZODB. I've thus far been unable to write a unit test which
> demonstrates the bug, but it is easily repeatable.  Anybody have an idea
> what might be going on here?

Never mind me, this is already fixed. :)

Alec