[Zope] dtml-with and only

[Michel Pelletier]

Barry A. Warsaw wrote:
> 
> Thanks for the suggestion and explanation guys.  Just to follow up,
> Michel's suggestion to use <dtml-with aq_explicit> to turn off
> acquisition did not work.  Loren's suggestion to test on
> "hasProperty('nickname')" did the trick nicely.  For completeness,
> here's the DTML for my current Breadcrumbs DTML method.

Oh did I say <dtml-with aq_explicit>? ;)

My bad, this was my wrong suggestion:

<dtml-with obj only>
  <dtml-with aq_explicit>
    <dtml-if nickname>

...


The problem here is that the Nspace stack is masked and obj is pushed on
to it.  Then, aq_explicit is pushed on top of that, when a lookup for
'nickname' fails in aq_explicit, it drops down to the next object on the
stack, which is obj, which *is* an implicit acquirer, so it does find
nickname, which is why it doesn't work.

What I really meant to say was:

<dtml-if "_.hasattr(aq_explicit, 'nickname')">
  <dtml-var nickname>
<dtml-else>
  <dtml-var title_or_id>
</dtml-if>

In either case, Loren's suggestion is probably better and cleaner (but
would not work for non property attributes named nickname, you may have
a requirement for 'nickname' to be a SQLMethod, for example).

-Michel