From: "David A. Black" <dblack@...>
Date: 2004-07-03T02:59:52+09:00
Subject: Re: How to detect if variable has been defined yet?

Hi --

On Sat, 3 Jul 2004, gabriele renzi wrote:

> il Fri, 02 Jul 2004 17:40:40 GMT, Randy Lawrence <jm@zzzzzzzzzzzz.com>
> ha scritto::
> 
> 
> defined? may be useful. Anyway, writing:
> 
> if variable
>  variable+=1
> else
>  variable=0
> end
> 
> should do just fine
> 

Have you tried it? :-)

$ ruby
if variable; variable += 1; else variable = 0; end
^D
-:1: undefined local variable or method `variable' for
main:Object (NameError)

I think you'd have to use defined?, or conditionally initialize the
variable:

  x ||= 0
  x += 1

(Note that you can't condense that into (x ||= 0) += 1, though you
could do: x = (x ||= 0) + 1 )


David

-- 
David A. Black
dblack@wobblini.net