オブジェクトのインスタンスメソッドを調べる

RubyのことはRubyに聞け

class Object
  def tell_me_methods
    self.class.instance_methods(false).map{|m|
      res = begin
        send(m)
      rescue=>e
        e.message
      end

      [ m, res ]
    }.sort_by{|k,v| v.class.to_s }.to_h
  end
end

1.tell_me_methods

{:even?=>false,
 :zero?=>false,
 :size=>8,
 :succ=>2,
 :bit_length=>1,
 :-@=>-1,
 :magnitude=>1,
 :~=>-2,
 :abs=>1,
 :to_f=>1.0,
 :>=>"wrong number of arguments (0 for 1)",
 :fdiv=>"wrong number of arguments (0 for 1)",
 :**=>"wrong number of arguments (0 for 1)",
 :modulo=>"wrong number of arguments (0 for 1)",
 :%=>"wrong number of arguments (0 for 1)",
 :===>"wrong number of arguments (0 for 1)",
 :====>"wrong number of arguments (0 for 1)",
 :<=>=>"wrong number of arguments (0 for 1)",
 :divmod=>"wrong number of arguments (0 for 1)",
 :>==>"wrong number of arguments (0 for 1)",
 :<=>"wrong number of arguments (0 for 1)",
 :<==>"wrong number of arguments (0 for 1)",
 :div=>"wrong number of arguments (0 for 1)",
 :inspect=>"1",
 :|=>"wrong number of arguments (0 for 1)",
 :^=>"wrong number of arguments (0 for 1)",
 :[]=>"wrong number of arguments (0 for 1)",
 :<<=>"wrong number of arguments (0 for 1)",
 :>>=>"wrong number of arguments (0 for 1)",
 :/=>"wrong number of arguments (0 for 1)",
 :*=>"wrong number of arguments (0 for 1)",
 :-=>"wrong number of arguments (0 for 1)",
 :+=>"wrong number of arguments (0 for 1)",
 :to_s=>"1",
 :&=>"wrong number of arguments (0 for 1)",
 :odd?=>true}

wrong number of argumentsは自分で叩くしかない（汗