From: Robert Klemme <shortcutter@...>
Date: 2008-05-02T16:39:31+09:00
Subject: Re: Please explain nuances of ||=

2008/5/2 Rick DeNatale <rick.denatale@gmail.com>:
>  So:
>
>  1) In Ruby x ||= y does no assignment if x evaluates to true, and x
>  &&= y does no assignment if x evaluates to true.
>  2) x || x = y, and x && x = y are much better first approximations of
>  how x ||= y and x &&= y than x = x || y, and x = x && y, despite what
>  K&R say.
>  3) I say first approximations because of David Black's observation
>  that x ||= y and x || x = y differ when x is undefined.
>
>  In summary:
>
>  That's the way that Ruby works. Ruby ain't C, or C++ or Java.

Nice summary!  And, if you think about it from a usability perspective
it does make the most sense the way it is.

1. you do not want to spent CPU cycles for assigning the same object
to a reference

2. more importantly, in the case of Hash you do not want the Hash to
change (which it would do if ||= were implemented differently as I
have demonstrated earlier).

I'm out.

Cheers

robert

-- 
use.inject do |as, often| as.you_can - without end