Tuesday Tricks - Regex Posix Shortcuts

Hate typing redundant regular expressions? Me too. How often have you typed the regex [a-zA-Z0-9]?

Posix character classes are here to save the day. You can replace a-zA-Z0-9 with [:alnum:]. [:alnum:] is the posix character class and there’s a whole slew of them at your disposal. Use them in Ruby like so:

'-- I have 37 dollars --' =~ /[[:alnum:]]/ #=> 3
'-- I have 37 dollars --' =~ /[[:digit:]]/ #=> 10
'-- I have 37 dollars --' =~ /[[:space:]]/ #=> 2

Note: An expression with =~ returns the first position in the string which matches the regex.

Check out the full list of posix character classes and determine how you can prettify your expressions.

This Tuesday’s Trick

Posix character classes won’t prevent global warming but they sure can help make your regular expressions more readable.

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