Matching unicode characters in a Ruby (1.9+) regexp

On Ruby 1.9+, standard ruby character classes like \w, \d will only match 7-Bit ASCII characters:

Copy"foo" =~ /\w+/   # matches "foo"
"füü" =~ /\w+/   # matches "f", ü is not 7-Bit ASCII

There is a collection of character classes that will match unicode characters. From the documentation:

• /[[:alnum:]]/ Alphabetic and numeric character
• /[[:alpha:]]/ Alphabetic character
• /[[:blank:]]/ Space or tab
• /[[:cntrl:]]/ Control character
• /[[:digit:]]/ Digit
• /[[:graph:]]/ Non-blank character (excludes spaces, control characters, and similar)
• /[[:lower:]]/ Lowercase alphabetical character
• /[[:print:]]/ Like [[:graph:]], but includes the space character
• /[[:punct:]]/ Punctuation character
• /[[:space:]]/ Whitespace character ([[:blank:]], newline, carriage return, etc.)
• /[[:upper:]]/ Uppercase alphabetical
• /[[:xdigit:]]/ Digit allowed in a hexadecimal number (i.e., 0-9a-fA-F)
• /[[:word:]]/ A character in one of the following Unicode general categories Letter, Mark, Number, Connector_Punctuation
• /[[:ascii:]]/ A character in the ASCII character set

So:

Copy"füü" =~ /[[:alpha:]]+/   # matches "füü"
"‎१४" =~ /[[:digit:]]+/    # matches "१४"