From: Joel VanderWerf <vjoel@...>
Date: 2008-05-09T09:26:02+09:00
Subject: Re: Doing an AND in regexp char class

Todd Benson wrote:
> I'm drawing a blank here with this one.  Why doesn't this work then...
> 
> irb(main):006:0> r = /\A[oh]*\z/
> => /\A[oh]*\z/
> irb(main):007:0> s = "hello, there"
> => "hello, there"
> irb(main):008:0> r === s
> => false

Maybe I'm confused about was wanted originally. The above tests the 
following condition:

   (set of chars occurring in given string)
      is_a_subset_of
   (given set of chars).

irb(main):007:0> /\A[oh]*\z/ === "hohoho"
=> true
irb(main):008:0> /\A[oh]*\z/ === "ho ho"
=> false

If you want superset instead of subset, this works:

irb(main):013:0> /(?=.*h)(?=.*o)/ === "h o"
=> true

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407