From: Matthew Kerwin <lists@...>
Date: 2013-04-24T13:42:26+09:00
Subject: Re: what is the $- magic global?

Julio Olivera wrote in post #1106717:
> If you try it on http://repl.it/, $- immediately returns nil. Perhaps on
> irb the interpreter is waiting for more input? I can't test it right
> now,
> but what happens if you write something like the following?
>
>> $-x = 42
>> $-
>> x
>
> Julio
> @_joliv <http://twitter.com/_joliv>
>

I think that's the right track.  There's something a little bit magic 
going on in IRB, because the second line is treated as a whole new line, 
thus:

irb(main):001:0> $-x = 42
=> 42
irb(main):002:0> $-
irb(main):003:0> x
NameError: undefined local variable or method `x' for main:Object
  from (irb):3
  from /usr/local/bin/irb21:12:in `<main>'
irb(main):004:0> $-
irb(main):005:0> 1
=> 1

Whatever it is, I guess the upshot is "don't use $- at the end of a line 
in IRB".

-- 
Posted via http://www.ruby-forum.com/.