[Zope] How to check if a string contains some characters??

Sorry to bother you, Is there a simple way to check if a string contain only this values: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789.-_" and otherwise raise an error? Thank you in advice, Marcello -- ---------------------------------------- Marcello Lupo Project Manager Atis Srl Via dell'Artigliere 2 37014 Castelnuovo del Garda (VR) Tel. +39-0457570960 - Fax +39-0457571268 E-mail: lupo@atisworld.com http://www.atisworld.com -----------------------------------------