From: Dave Thomas <Dave@...>
Date: 2001-09-19T01:06:50+09:00
Subject: [ruby-talk:21338] Re: if before or if after?

Paul Brannan <pbrannan@atdesk.com> writes:

> (1) If I do this:
> 
>   x = '' if not defined?(x)
>   p x
> 
> Then I get this:
> 
>   nil
> 
> (2) But if I do this:
> 
>   if not defined?(x) then x = '' end
> 
> Then I get this:
> 
>   ""
> 
> (3) But, if I do this:
> 
>   x = '' if not defined?(x)
>   if not defined?(x) then x = '' end
>   p x
> 
> Then I get this:
> 
>   nil
> 
> What's going on here?

Just seeing the assignment to 'x' defines it. In

   x = '' unless defined? x

'x' is defined by the assignment, so the assignment doesn't execute :)


Dave