From: Andrew McGuinness <a.mcguinness@...>
Date: 2006-01-13T07:13:06+09:00
Subject: Re: Newbie question about multiple assignments

David Vallner wrote:
> On Thu, 12 Jan 2006 15:09:01 +0100, <dblack@wobblini.net> wrote:
> 
>>
>> An assignment expression returns its right-hand side.  In this case,
>> that's [b, a = a, b]:
>>
>> a = 1
>> b = 2
>> [b, a = a, b] => [2,1,2]
>>
> 
> 
> Ah well, for some strange reason I thought the parser would check for a  
> parallel assignment form inside the array constructor as well. 
> Apparently  not... Right, that example pretty much clears the issue up.
> 
Within method arguments, the "," gets parsed as an argument separator 
not an array separator:

irb(main):094:0> puts( a,b = 1,2 )
1
1
2
=> nil
irb(main):095:0> puts( ( a,b = 1,2 ) )
1
2
=> nil



irb(main):103:0> a,b=1,2
=> [1, 2]
irb(main):104:0> a,b=(b,a=a,b)
=> [1, 2]
irb(main):105:0> a
=> 1
irb(main):106:0> b
=> 2