From: Rein Henrichs <reinh@...>
Date: 2010-06-08T05:30:06+09:00
Subject: Re: Question about abbreviated indexing assignments

On 2010-06-07 12:18:39 -0700, Rick DeNatale said:

> On Mon, Jun 7, 2010 at 1:05 PM, Rein Henrichs <reinh@reinh.com> wrote:
>> It is commonly thought that x <operator>= y is exactly equivalent to x = x
>> <operator> y in all cases. What you have just demonstrated is that,
>> presumably for performance reasons, h[key] ||= value is in fact equivalent
>> to h[key] || h[key] = value, rather than h[key] = h[key] || value. This
>> prevents a second lookup in the case where k[key] exists and is not nil or
>> false.
>> 
> 
> x ||= y is NOT equivalent to x = x || y
> 
> Instead a closer approximation is
> 
>   x || x = y
> 
> http://talklikeaduck.denhaven2.com/2008/04/26/x-y-redux

Good explanation in that post, Rick. Thanks!

-- 
Rein Henrichs
http://puppetlabs.com
http://reinh.com