I just ran across this, and can't figure out what's happening.  the
show_regexp method is as shown on p73 of the Pickaxe 2nd ed.

irb(main):013:0> show_regexp("comparison is", /[:alpha:][^.?!\s'"]*/)
=> "com<<parison>> is"
irb(main):014:0> show_regexp("comparison is", /[:alpha:][^\s]*/)
=> "com<<parison>> is"
irb(main):015:0> show_regexp("comparison is", /[:alpha:][\S]*/)
=> "com<<parison>> is"
irb(main):016:0> show_regexp("comparison is", /[a-zA-Z][\S]*/)
=> "<<comparison>> is"
irb(main):017:0> show_regexp("comparison is", /[a-zA-Z][^\s]*/)
=> "<<comparison>> is"

It looks like the Posix :alpha: character class doesn't include c, o, or m?!?

Or am I missing something?

-- 
Rick DeNatale