Converting constants to human readable strings

bit_fiddler.rb

class Foo
  Alpha = 1
  Beta  = 2
  Gamma = 4

  @@opts = {
    Alpha => 'alpha',
    Beta  => 'beta',
    Gamma => 'gamma'
  }

  def display(num)
    flags = num
    str   = ''


    @@opts.each{ |key,val|
      if flags & key > 0
        if str.empty?
          str << val
        else
          str << ",#{val}"
        end
        flags &= ~key
      end
    }

    p str
  end
end

Foo.new.display(Foo::Alpha) # Works
Foo.new.display(Foo::Alpha|Foo::Beta) # Works
Foo.new.display(Foo::Alpha|Foo::Beta|Foo::Gamma) # Works after all with valid values. :)