From: Robert Klemme <bob.news@...>
Date: 2006-02-28T22:38:35+09:00
Subject: Re: Iterators and Assigment

Godspeed wrote:
> Consider...
>
> def fred
>   yield $k
>   puts "in fred #{$k}"
> end
>
> $k=2
> fred {|o| o = 3}
> puts "outside fred #{$k}"
>
> produces:
>
> in fred 2
> outside fred 2
>
> why is $k still 2 after the call to fred?

Because Ruby does call by value where values are object references.  Same
holds for blocks and their parameters.  There is no implicit aliasing
between k$ and o.  When the block is invoked you get a new reference which
initially points to the same instance as $k.  Then you assign it and it
points to some other object leaving $k still pointing to the old instance.

Kind regards

    robert