From: itsme213@... (you CAN teach an old dog ...)
Date: 2003-06-13T15:50:31+09:00
Subject: Re: Confused about to_s in Ruby / irb

"Hal E. Fulton" <hal9000@hypermetrics.com> wrote > I guess you know
about p and puts, right?

>   puts obj
> will call obj.to_s, but
>   p obj
> will call obj.inspect instead.

Sounds reasonable, but it does not explain the behavior below. It
seems (p x) calls x.inspect if it is defined; otherwise it calls
x.to_s

>class None; end        
  ==> nil
>p None.new
  ==> #<None:0x2ac6110>
>puts None.new
  ==> #<None:0x2ac46a0>


>class To_S; def to_s; "to_s  "; end; end  
  ==> nil
>p To_S.new       # how come?
  ==> to_s
>puts To_S.new
  ==> to_s


>class Inspect; def inspect; "inspect "; end; end 
  ==> nil
>p Inspect.new
  ==> inspect
>puts Inspect.new
  ==> #<Inspect:0x2ad97a8>


>class Both
>  def to_s; "Both: to_s "; end
>  def inspect; "Both: inspect "; end
>end
  ==>nil

>p Both.new
  ==> Both: inspect
>puts Both.new
  ==> Both: to_s