From: dblack@...
Date: 2006-08-13T08:39:22+09:00
Subject: Re: Newbie at ruby - syntactic sugar for Range / Array

Hi --

On Sun, 13 Aug 2006, Rick DeNatale wrote:

> On 8/12/06, dblack@wobblini.net <dblack@wobblini.net> wrote:
>
>> So *0..3 is almost like saying: you're a range, but pretend that
>> you're a thing that can be un-arrayed, namely an array.  That seems to
>> be the purpose of the * in this case -- to "trick" the range into
>> thinking it's an array.
>> 
>> If you look at ranges as array-like lists of values in the first place
>> (which I don't), then it might make sense in a less convoluted way :-)
>
> Or you can think of the * before the last rvalue in an assignment as a
> signal to replace the rvalue with a series of rvalues obtained from
> the elements of the array resulting from sending to_ary to the
> original rvalue.
>
> The original rvalue doesn't need to be an array, or a range, just
> anything which responds to to_ary
>
> And actually in Ruby 1.8, it looks like it can be any object, since it
> seems to actually use to_a instead of to_ary which is defined in
> Object to return an array containing the receiver.  But this is
> supposed to change in Ruby 1.9

Yes, that's a more cogent explanation, and it accounts for:

   a, b = "abc\ndef"  =>  a == "abc\n", b = "def"

So the only weird thing is that ranges can turn themselves into arrays
:-)


David

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