schema and at least one of the validators is not empty

"Carl S. Yestrau Jr." <carl-BRjM4l+eP8h0QxGK/[email protected]> Tue, 25 Jan 2011 00:09:22 -0800
Newsgroups gmane.comp.python.formencode
Message-ID <[email protected]>
class AtLeastOneOfThese(formencode.Schema):
   a = validators.String(not_empty=False)
   b = validators.String(not_empty=False)
   c = validators.String(not_empty=False)
   # how do I create a chained validator so even though a, b, c are
optional at least one of a, b or c is not_empty?

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