From: Robert Klemme <shortcutter@...>
Date: 2008-03-25T23:52:29+09:00
Subject: Re: numbers of a record in an array

2008/3/25, Jesús Gabriel y Galán <jgabrielygalan@gmail.com>:
> On Tue, Mar 25, 2008 at 1:49 PM, Robert Klemme
>
> <shortcutter@googlemail.com> wrote:
>  > 2008/3/25, Jesús Gabriel y Galán <jgabrielygalan@gmail.com>:
>  >  > On Tue, Mar 25, 2008 at 11:23 AM, Robert Klemme
>  >  >  <shortcutter@googlemail.com> wrote:
>
>
> >  No, this has nothing to do with immediate values.  The reason why this
>  >  works is that an operation is used that creates a new instance
>  >  (Fixnum#+ in this case) and uses assignment to place a new value on
>  >  every iteration.  This also works with arrays and other non immediate
>  >  and even mutable instances:
>  >
>  >  irb(main):001:0> collector = Hash.new []
>  >  => {}
>  >  irb(main):002:0> 10.times {|i| collector[i%3] += [i]}
>  >  => 10
>
>
> Ah, ok, now I see what you mean. I didn't consider this case, because
>  you are creating intermediate arrays every iteration. In my head I was
>  equating the += for Fixnums with << for Arrays in this idiom, if you see
>  what I mean.

That's what I would usually do. But you asked for the reason why the
default value setting was sufficient.  So I demonstrated with a
mutable object and + - could have been anything else (BigDecimal#+ or
String#+ for example).

Cheers

robert

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