[Zope] Newbie dereferencing problem

[Kirk Strauser]

I apologize for the (probably FAQ) newbie problem.  FedEx hasn't delivered
my copy of "The Zope Book" or "Programming Python" yet, so please forgive
me.

Suppose I have the name of an object in variable `foo'.  I would like to
test for the existence of the named object.  Suppose that foo=='bar'.  The
following won't work:

  <dtml-if foo>
    <br>Yep!
  </dtml-if>

because `foo' will always have a value.  How, then, can I see if `bar'
exists?

A million thanks,
-- 
Kirk Strauser