From: RichardOnRails <RichardDummyMailbox58407@...>
Date: 2008-08-29T03:30:17+09:00
Subject: Re: Dumb "array of arrays" question

On Aug 28, 1:07 pm, Adam Shelly <adam.she...@gmail.com> wrote:
> On 8/28/08, Thomas B. <tpr...@gmail.com> wrote:
>
>
>
> > Hello Richard,
>
> > RichardOnRails wrote:
> > > More importantly,  according to my tests below,  dup'ing an array does
> > > NOT make a new array.  It returns the (address of/pointer to) the same
> > > old array.
>
> > dup'ing an array DOES make a new array, only the new array looks like
> > the old one, because Array#inspect doesn't return the address of the
> > array so you cannot see if it is exactly the same instance or not.
> > > 3: [#<Object:0x2808138>]; #<Object:0x2808138>; Array
> > > 4: [#<Object:0x2808138>]; #<Object:0x2808138>; Array
>
> > The [#<Object:0x2808138>]'s here are in fact different objects, only
> > they look the same.
>
> You can prove they are different objects this way:
> code:
>    a = [Object.new]; ad = a.dup
>    puts a.inspect+ ", #{a.object_id}"
>    puts ad.inspect+ ", #{ad.object_id}"
> output:
> [#<Object:0x2842310>], 21107090
> [#<Object:0x2842310>], 21107070
>
> -Adam

Hi Adam,

Thanks for example.  My mistake was thinking that a.inspect, which
yielded [#<Object:0x2842310>] was yielding the a's object_id.

I speculated that inspect yielded its receiver's content's object_id.
That's wrong, as evidenced by the following code.  So is inspect
returning in this instance?

Best wishes,
Richard

a = [x]
ad = a.dup

puts "1: " + a.object_id.to_s+ "; " + a[0].object_id.to_s + "; " +
a.inspect
puts "2: " + ad.object_id.to_s + "; " + ad[0].object_id.to_s + "; " +
ad.inspect

1: 20987380; 20987470; [#<Object:0x2807c9c>]
2: 20987370; 20987470; [#<Object:0x2807c9c>]