From: matz@... (Yukihiro Matsumoto)
Date: 2001-09-19T01:21:49+09:00
Subject: [ruby-talk:21339] Re: if before or if after?

Hi,

As a general rule, a local variable start to exist when an assignemt
to the variable is seen first, even if the assignemt is not executed
at runtime.

In message "[ruby-talk:21332] if before or if after?"
    on 01/09/19, Paul Brannan <pbrannan@atdesk.com> writes:

|(1) If I do this:
|
|  x = '' if not defined?(x)
|  p x

'x' start to exist at "x=''", so that defined?(x) is always true.

|(2) But if I do this:
|
|  if not defined?(x) then x = '' end

A local variable 'x' is not exist at "defined?(x), so it's always
false (unless it is defined previously).

|(3) But, if I do this:
|
|  x = '' if not defined?(x)
|  if not defined?(x) then x = '' end
|  p x

'x' start to exist at "x=''", so that both defined?(x) is always true.

|What's going on here?

Do you get it?

							matz.