[Zope] Very lightweight form validation

[Kirk Strauser]

I need to do some minimal validation on a few forms.  The built-in 
typechecking (http://www.zope.org/Members/Zen/howto/FormVariableTypes) does 
about 99% of what I need, with the exception of outputting useful error 
messages.

I've looked at some of the various form-processing add-ons but all of them 
see very "heavy" when what I mainly want to do is ensure that the user 
remembered to fill in their last name, and if not, tell them that they need 
to enter it and try again.  Seriously, that's about the sophistication 
level I'm targeting.

Any suggestions?
-- 
Kirk Strauser
The Day Companies