module CoreExt
  module Hash



    def pick(*picks)
      picks = picks.flatten
      picks.inject({}) {|result, key| self.key?(key) ? result.merge(key => self[key]) : result}
    end



    def pick!(*picks)
      picks = picks.flatten
      keys.each {|key| self.delete(key) unless picks.member?(key) }
    end



    def except(*picks)
      result = self.dup
      result.except!(*picks)
      result
    end



    def except!(*picks)
      picks = picks.flatten
      keys.each {|key| self.delete(key) if picks.member?(key) }
    end



    def inspect!(depth=0)
      s = ""
      self.each do |k,v|
        s << (" " * depth)
        s << k
        s << ": "
        if v.is_a?(Hash)
          s << "{\n"
          s << v.inspect!(depth + 2)
          s << (" " * depth)
          s << "}"
        elsif v.is_a?(Array)
          s << v.inspect
        else
          s << v.to_s
        end
        s << "\n"
      end
      s
    end



  end
end

Hash.send :include, CoreExt::Hash