gistfile1.rb

# exhibit a
    {:conditions => case f.to_s
      when 'active'   then {:state => @@states[2]}
      when 'disabled' then {:state => @@states[0..1]}
      when 'all'      then {}
      else                 {:state => @@states[3]}
    end}

# exhibit b
    case f.to_s
      when 'active'   then {:conditions => {:state => @@states[2]}}
      when 'disabled' then {:conditions => {:state => @@states[0..1]}}
      when 'all'      then {}
      else                 {:conditions => {:state => @@states[3]}}
    end

# exhibit c
    return if f.to_s == 'all'
    state = case f.to_s
      when 'active'   then @@states[2]
      when 'disabled' then @@states[0..1]
      else                 @@states[3]
    end
    {:conditions => {:state => state}} # I shouldn't have forgotten this!

# exhibit d
    # Everyone loves Hash!
    @@states = {'active' => {'some' => 'conditions'},
      'disabled' => {'other' => 'conditions'}}
    @@states[f].nil?? {} : {:conditions => {:state => @@states[f]}}