On Thu, May 8, 2008 at 7:00 PM, Joel VanderWerf <vjoel@[...].edu>  wrote:
>  Todd Benson wrote:
> >
> > On Thu, May 8, 2008 at 6:07 PM, ara.t.howard <ara.t.howard@[...].com>
> > wrote:
> >>
> >> On May 8, 2008, at 3:40 PM, Todd Benson wrote:
> >>>
> >>> This question arises out of a couple of recent threads and may or may
> >>> not be a Ruby-specific question.
> >>>
> >>> I can check with a character class if one of the characters in the
> >>> class exists or does not exist, but can I use a regexp to check if a
> >>> string absolutely contains all of the characters in the class?
> >>>
> >>> Using a set perspective, I can do it like this in irb...
> >>>
> >>> s1 = "hello there"
> >>> s2 = "ohi"
> >>> (s2.unpack('c*') & s1.unpack('c*')).size == s2.size
> >>>
> >>> => false
> >>>
> >>> I use unpack to avoid creating a bunch of String objects, one for each
> >>> element in the array, which would happen if I used #split.  What I'm
> >>> wondering is if there is a way to do this with a simple regexp.
> >>>
> >>> Thanks,
> >>> Todd
> >>
> >> cfp:~ > cat a.rb
> >> class String
> >>  def all_chars? chars
> >>   tr(chars, '').empty?
> >>  end
> >> end
> >>
> >> p 'foobar'.all_chars?('rabof')
> >> p 'foobar'.all_chars?('abc')
> >> p 'foobar'.all_chars?('')
> >>
> >>
> >>
> >> cfp:~ > ruby a.rb
> >> true
> >> false
> >> false
> >
> > Cool :)  #tr is one of those useful methods I somehow consistently forget
> > about.
> 
>  But it can be done with regex, right? It's just more elegant with tr.
> 
>  class String
>   def all_chars? chars
>     if chars.empty?
>       empty?
>     else
>       /\A[#{chars}]*\z/ === self
>     end
>   end
>  end
> 
>  p 'foobar'.all_chars?('rabof')  # => true
>  p 'foobar'.all_chars?('abc')    # => false
>  p 'foobar'.all_chars?('')       # => false

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

Todd