From: David Vallner <david@...>
Date: 2006-01-12T21:49:44+09:00
Subject: Re: Newbie question about multiple assignments

On Thu, 12 Jan 2006 13:39:00 +0100, Michael Ulm  
<michael.ulm@isis-papyrus.com> wrote:

> Alex wrote:
>> irb(main):091:0> a=1
>> => 1
>> irb(main):092:0> b=2
>> => 2
>> irb(main):093:0> a,b=b,a
>> => [2, 1]
>> irb(main):094:0> a=1
>> => 1
>> irb(main):095:0> b=2
>> => 2
>> irb(main):096:0> a, b = b, a = a, b
>> => [2, 1, 2]                           <-- Why?
>>  What is the order for the assignments
>>
>
> Keep in mind, that
>
> a, b = c, d
>
> is just shorthand for
>
> a, b = [c, d]
>
> So, your expression
>
> a, b = b, a = a, b
>
> gets parsed as
>
> a, b = [b, a = a, b]
>
> and thus produces the observed behaviour.
>
> HTH,
>
> Michael
>
>


That doesn't seem to explain the return value [2, 1, 2] of the expression.

David Vallner