[Zope] Multiple selection property as list

[Alexander James Tucker]

Hi,

I have a ZClass based product with a property sheet which has a 
multiple selection property called "groups", listing the group or 
groups a person belongs to.

I'd like to be able to access this property as a list, so that I can 
create expressions like the following:

  <dtml-if expr="'Some group' in groups">
   ...
  </dtml-if>

However, in this expression, groups is treated as a string, so I get 
an error saying that the left hand side of the 'in' expression must 
be a character, not a string.

I can work around the problem by iterating over groups with dtml-in 
and creating a new list, something like this:

  <dtml-let grouplist="[]">
    <dtml-in groups>
      <dtml-call "grouplist.append(_['sequence-item'])">
    </dtml-in>
    <dtml-if "'Some group' in grouplist">
      ...
    </dtml-if>
  </dtml-let>

Can anyone see a better way of doing this?  If dtml-in can see the 
property as a list, why can't the 'in' operator?

Cheers,
Alex.