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From: Robert Klemme <shortcutter@googlemail.com>
Newsgroups: comp.lang.ruby
Subject: Re: How undefined values are handled with 'if' modifier.
Date: Sat, 08 Dec 2012 10:34:09 +0100
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On 12/07/2012 07:02 PM, michael.j.cannon@gmail.com wrote:
> Why do these two expressions give different results when foo is undefined?
>
> foo if (foo = 3)          # => NameError: undefined local variable or method `foo' for main:Object
> if (foo = 3); foo end  # => 3
>
> Granted, an operator like ||= does something handy, even though it's inconsistent with  foo = foo || 3
> but the if-expression-vs-modifier inconsistency just seems wrong.

That has been discussed numerous times on ruby-talk.  That last 
discussion is just a few weeks back.

Bottom line: syntactic order in the source determines from when on a 
local variable is defined.

Cheers

	robert