Still, for $3, Patterns is a helpful addition to the toolkit of anyone who builds regular expressions with regularity. If you work with text, you owe it to yourself to learn regular expressions — and using Patterns can help you figure out exactly what your patterns are capturing.
(Of course, you don't need a dedicated Mac app to test out regular expressions. The website regexpal does it in a web browser, and the excellent — and free — text editor TextWrangler offers a complete regular-expression-based search-and-replace system. But for $3, Patterns's native Mac interface and search-and-replace preview are worth the paltry premium.)
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