From: Bertram Scharpf <lists@...>
Date: 2009-08-19T12:28:43+09:00
Subject: Re: if defined on var

Hi,
Am Mittwoch, 19. Aug 2009, 11:22:18 +0900 schrieb Derek Smith:
> table_exists = db.execute( ...)
> 
> if defined?(table_exists)
>    p "yes"
> end
> exit
> 
> Why does this print "yes"?

  irb(main):001:0> x = nil
  => nil
  irb(main):002:0> defined? x
  => "local-variable"
  irb(main):003:0> defined? y
  => "method"
  irb(main):004:0> defined? z
  => nil
     ^^^
    ^^^^^
  irb(main):005:0> y
  ArgumentError: wrong number of arguments (0 for 1)
    from (irb):5:in `y'
    from (irb):5
  irb(main):006:0>

Ugh, I did not know that `y' is a method.

Be aware that `defined?' is not an operator but examines the next
token.

Bertram


-- 
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de