From: "David A. Black" <dblack@...>
Date: 2004-09-17T11:25:50+09:00
Subject: Re: Ex-Perl coders: Howz it feel to convert to Ruby?

Hi --

On Fri, 17 Sep 2004, Brian Wisti wrote:

> 
> --- "David A. Black" <dblack@wobblini.net> wrote:
> 
> > Hi --
> > 
> > On Fri, 17 Sep 2004, Brian Wisti wrote:
> > 
> > > 
> > > --- Nate Smith <nsmith5@nist.gov> wrote:
> > > 
> > > > Try
> > > > 
> > > > print "a" + 1
> > > > 
> > > > Won't work -- you have to do
> > > > 
> > > > print "a" + 1.to_s
> > > > 
> > > > 
> > > > Nate
> > > 
> > > That "+" means you're building a new string from two Strings. Since
> > the
> > > second operand is not a String, the conversion has to be explicit.
> > 
> > If the second operand responds to to_str, then its response to to_str
> > will be used in cases where only a string will do:
> > 
> >   irb(main):016:0> obj = Object.new
> >   => #<Object:0x402a6e94>
> >   irb(main):017:0> puts "this is an " + obj
> >   TypeError: cannot convert Object into String
> >           from (irb):17:in `+'
> >           from (irb):17
> >           from :0
> >   irb(main):018:0> def obj.to_str; "implicit string representation!";
> >   end
> >   => nil
> >   irb(main):019:0> puts "this is an " + obj
> >   this is an implicit string representation!
>
> So we just have Fixnums and similar types not responding to to_s?
> Interesting...

No, they do respond to to_s, but not to to_str.  It's to_str that
provides this kind of masquerading facility.  


David

-- 
David A. Black
dblack@wobblini.net