From: "Gray, Jeff" <jeff.gray@...>
Date: 2002-06-05T11:11:06+09:00
Subject: Is this a bug in the defined? operator?

The behavior of the following code seems like a bug to me:

----
[1, 2, 3, 4].each { |x|
  if defined? foo
    puts "foo is defined"
  else
    puts "foo not defined"
    foo = true
  end
}

[1, 2, 3, 4].each { |x|
  if (x % 2) == 0
    if defined? bar
      puts "bar is defined"
    else
      puts "bar not defined"
      bar = true
    end
  else                           # <--
    if defined? bar              # <--
      puts "bar is defined"      # <--
    else                         # <--
      puts "bar not defined"     # <--
      bar = true                 # <--
    end                          # <--
  end
}
----

This produces:

foo not defined
foo not defined
foo not defined
foo not defined
bar is defined
bar not defined
bar is defined
bar not defined

In other words, in the second loop, inside the "highlighted" 'else' clause
-- and only inside that clause -- 'defined? bar' evaluates to
"local-variable(in-block)" for some reason.  This is either a bug or
something so subtle it's beyond me...

I didn't find anything in ruby-talk archives about it, and the behavior is
consistent among the following versions:

ruby 1.6.5 (2001-09-19) [i686-linux]
ruby 1.6.7 (2002-06-04) [i686-linux]
ruby 1.7.2 (2002-06-04) [i686-linux]

Cheers,

  - jeff