From: Robert Klemme <bob.news@...>
Date: 2003-11-17T10:25:26+09:00
Subject: Re: Messages to nil


"dhtapp" <dhtapp@cox.net> schrieb im Newsbeitrag
news:2c6sb.12896$7B2.12145@fed1read04...
> Hi,
>
> One of the things I got accustomed to in Objective C was nil's behavior
as a
> universal message sink:  You could send nil anything, and you'd get nil
> back.
>
> No big deal, really, except that it made message cascades (which in Ruby
> would look like Java- or OGNL-style keypaths) a bit easier to code,
without
> having to stop off at every point in the path and use an if-statement to
see
> if there was a real object still listening.  When I switched over to
> predominately using Java a few years back, it took me a couple of
painful
> days to change that habit (not to mention remembering to use "null"
> instead...literally the most besetting annoyance I inflicted on myself
in
> trying to learn Java).
>
> Just curious:  would it be worth petitioning the Power That Be for a
global
> switch that induced that kind of behavior in nil?  Would there be any
> catastrophic consequences?  (Please be gentle; I still have only the
> faintest clue what I'm doing with Ruby, except enjoying it a great
deal...)

Well, instead of checking at each point you can simply catch
NoMethodError:

begin
  "foo".bar.baz.foo.doit( "yes" )
rescue NoMethodError => e
  puts "ERROR in method #{e.name}( #{e.args.inspect} )"
end

Btw: the same works in Java, only there you'd probably catch
NullPointerException.

Regards

    robert