From: Brian Candler <B.Candler@...>
Date: 2007-05-29T22:02:48+09:00
Subject: Re: Overriding to_s

On Tue, May 29, 2007 at 09:55:04PM +0900, kimersen@gmail.com wrote:
> > Because puts will revert to something else (likely #inspect) if the
> > result of to_s is not String.
> >
> > irb(main):001:0> class Foo
> > irb(main):002:1> def to_s; self.class.to_s end
> > irb(main):003:1> end
> > => nil
> > irb(main):004:0> puts Foo.new
> > Foo
> > => nil
> >
> > Kind regards
> >
> >         robert
> 
> My understanding of puts is that it puts the result of to_s.
> puts n and puts n.to_s are the same then and should in my example
> print the same.
> But they don't and that is for me a bit annoying because I thought I
> understood what was going on.

Yes, but what do you expect "puts" to do when it calls to_s on an object,
but the result is not a string? Raise an exception perhaps? It's more
friendly for puts to have a fallback behaviour.

Note: there's one other special case I'm aware of. If you do
   puts nil
then you get the string "nil" printed (plus newline). However, nil.to_s is
the empty string.

Regards,

Brian.