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From: Gianfranco Bozzetti on 11 Aug 2010 02:53
Kaye Ng wrote:
> #Run this code
>
> x=[2,6,5,9]
> y = x
> puts x
> puts
> puts y
> puts
>
> x=[1,2,3,4]
> puts x
> puts
> puts y
> -------------------------------------
> #this also
>
> x=[2,6,5,9]
> y = x
> puts x
> puts
> puts y
> puts
>
> x.pop
> puts x
> puts
> puts y
> ---------------------------
>
> I understand the first code, y was still pointing to [2,6,5,9]
> but isn't the second code similar? shouldn't y still be [2,6,5,9] ?
>
> Or is the method pop an exemption in this case?
>
> Beginner here. Thanks everyone!


In the second snippet x.pop removes the last
element, leaving x=[2,6,5], and y points to
the modified array.

HTH gfb
--
Posted via http://www.ruby-forum.com/.

From: Brian Candler on 11 Aug 2010 06:38
Kaye Ng wrote:
> #Run this code
>
> x=[2,6,5,9]
> y = x

x and y are pointing to the same array

> x=[1,2,3,4]

Now x is pointing to a different array (look at x.object_id and
y.object_id)

> x=[2,6,5,9]
> y = x

x and y are pointing to the same array

> x.pop

x and y are still pointing to the same array. You modified this array by
popping an element off it.

So you need to remember:
* Every value in Ruby is an object *reference*
* Most objects in Ruby are mutable, i.e. their internal state can
change.

>> a = "hello"
=> "hello"
>> b = a
=> "hello"
>> a.upcase!
=> "HELLO"
>> a
=> "HELLO"
>> b
=> "HELLO"
--
Posted via http://www.ruby-forum.com/.

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