[ZPT] how do I test the existence of a variable?

[seb bacon]

On Thu, 2002-03-21 at 17:44, Casey Duncan wrote:
> seb bacon wrote:
> > Thanks to everyone's replys, but we're still not there!
> > 
> > Harry's response comes closest to my requirements:
> 
> Perhaps this is indicative of a thinker than normal wall around my 
> cranium, but I fail to see why this isn't what you want:
> 
> <p metal:define-macro="foo"
>     tal:define="bar bar | python:<some expression>">
>     ...use bar to construct wonderous things...
> </p>


Hey, I *must've* already tried that.  Surely.  There must be some
mistake ;-)

Shane answered my specific question, but your solution works fine.

Thanks for pointing out my brain barf.

seb