[Zope-dev] More comments on ZPatterns

[Phillip J. Eby]

At 03:10 AM 7/6/00 +0000, Scott Parish wrote:
>
>Anyway, Under Zope 2.2, the 'Upon' property of a trigger doesn't have a list 
>of 'event_kinds'.  I think this is related to an earlier post where i 
>complained about zope 2.2 not being able to get such values (for select 
>types) from aquisition, or in this case from a seperate property in its 
>class.  Has anybody thought of a way to address this problem, as it didn't
>sound like the official zope distribution wants to act the way that would
>allow the 'Upon' property to get its proper values right now. (no, i'm
>not going to go off about that <g>)  

In our working copy of ZPatterns, Ty has patched ZPatterns to make the list
a property.  Personally, I think this recent behavior of 2.2 is broken, and
I hope to submit a patch soon to the Collector to fix it, so that we can
back out the ZPatterns patch.  It should not be necessary for the value of
a select/multiselect property to be another *property*, as this will break
other people's code besides ZPatterns.  The Zope documentation in
OFS/PropertyManager.py explicitly states:

    For 'selection' and 'multiple selection' properties, there is an
    addition item in the property dictionay, 'select_variable' which
    provides the name of a property or method which returns a list of
    strings from which the selection(s) can be chosen.

So this is pretty clearly broken in 2.2.


>Also, should i not be trying to use ZPatterns 4aX under Zope 2.2?  I thought
>i read that to use triggers a person should use Zope 2.2, but it doesn't
>appear this has been tested under 2.2. (although it is alpha, i haven't 
>forgotten that)

Yeah, you can use it under 2.2, although as you've pointed out, there is a
problem with the property issue.  It has been tested rather extensively
under 2.2, it's just that this one item hasn't been put out in a fix
release, because we were going to report it to the Collector as a bug (I'm
not sure if Ty has done so yet; it was right before my vacation that he
found the problem).

As for the warning about transactional issues with triggers under 2.1.x,
they have to do with triggers that update things stored in the ZODB, and
they will not always have problems.  It's just that transaction ordering
semantics are very different between 2.1.x and 2.2; 2.2 is pure FIFO where
2.1.x is a LIFO stack, even during the commit process.


>ZPatterns is starting to taste pretty sweet.  Keep up the good work!

Thanks.