creating an (inefficent) alternating regular expression from a list of options

Larry Bates larry.bates at
Tue Sep 9 15:19:04 CEST 2008 wrote:
> Pyparsing has a really nice feature that I want in PLY. I want to
> specify a list of strings and have them converted to a regular
> expression.
> A Perl module which does an aggressively optimizing job of this is
> Regexp::List -
> I really dont care if the expression is optimal. So the goal is
> something like:
> vowel_regexp = oneOf("a aa i ii u uu".split())  # yielding r'(aa|a|uu|
> u|ii|i)'
> Is there a public module available for this purpose?

Perhaps I'm missing something but your function call oneOf(...) is longer than 
than actually specifying the result.

You can certainly write quite easily:

def oneOf(s):
     return "|".join(s.split())


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