From: Bertram Scharpf <lists@...>
Date: 2009-12-31T23:15:14+09:00
Subject: Re: Why can't I use "or" here?

Hi,

Am Donnerstag, 31. Dez 2009, 11:24:26 +0900 schrieb Albert Schlef:
> (The problem is in both Ruby 1.8 and Ruby 1.9)
> 
> The expression:
> 
>   puts(nil || 4)
> 
> works as expected. It prints '4'.
> 
> But this expression:
> 
>   puts(nil or 4)
> 
> fails... it is a syntax error, for some mysterious reason.
> 
> Why? I thought the only diference between "or" and "||" is the
> precedence.

There's a difference between _grouping_ parentheses (like
begin...end) and _method_ _call_ parentheses:

  puts (nil or 4)           # vs.
  puts( nil or 4)

See:

  irb(main):001:0> $-w = true
  => true
  irb(main):002:0> puts( nil or 4)
  SyntaxError: compile error
  (irb):2: syntax error, unexpected kOR, expecting ')'
  puts( nil or 4)
              ^
          from (irb):2
  irb(main):003:0> puts (nil or 4)
  (irb):3: warning: (...) interpreted as grouped expression
  4
  => nil


Bertram


-- 
Bertram Scharpf
Stuttgart, Deutschland/Germany
*
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