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in reply to Regexp explanation

In addition to all answers you already have, in understanding/learning regex-en YAPE::Regex::Explain can be very useful:
use YAPE::Regex::Explain; print YAPE::Regex::Explain->new(qr/((\w|')+)/)->explain(); __DATA__ The regular expression: (?-imsx:((\w|')+)) matches as follows: NODE EXPLANATION ---------------------------------------------------------------------- (?-imsx: group, but do not capture (case-sensitive) (with ^ and $ matching normally) (with . not matching \n) (matching whitespace and # normally): ---------------------------------------------------------------------- ( group and capture to \1: ---------------------------------------------------------------------- ( group and capture to \2 (1 or more times (matching the most amount possible)): ---------------------------------------------------------------------- \w word characters (a-z, A-Z, 0-9, _) ---------------------------------------------------------------------- | OR ---------------------------------------------------------------------- ' '\'' ---------------------------------------------------------------------- )+ end of \2 (NOTE: because you're using a quantifier on this capture, only the LAST repetition of the captured pattern will be stored in \2) ---------------------------------------------------------------------- ) end of \1 ---------------------------------------------------------------------- ) end of grouping ----------------------------------------------------------------------