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comp.lang.ruby

String.insert newbie question

Marco Guiseppe

1/27/2007 1:01:00 AM

Hello,

I've only been checking out Ruby for a couple of days, but today I came
across this problem.

If I do this:

#!/usr/bin/env ruby -w

string1 = "abc"
string2 = string1

string2.insert(-1, "def")

puts string1
puts string2

Then the result is:

abcdef
abcdef


How come string1 gets changed?!?

Thanks,

Marco

--
Posted via http://www.ruby-....
4 Answers

Marco Guiseppe

1/27/2007 1:23:00 AM

0

Jason Mayer wrote:

>> check it out in irb.
>

> Hope that helps.

Thanks for clearing that up, didn't know about object_id. Is this
behaviour common in programming languages? Seems weird to me.

Then again I'm very new to all of this.

This means I could do

string1 = "abc"
string2 = string1
string3 = string2
string4 = string3

and they all will change if I change string 4. What can I do to keep
string1 stay the same even if I change string 4?

--
Posted via http://www.ruby-....

John Mettraux

1/27/2007 1:30:00 AM

0

On 1/27/07, Marco Guiseppe <kreatix@gmail.com> wrote:
> Jason Mayer wrote:
>
> >> check it out in irb.
> >
>
> > Hope that helps.
>
> Thanks for clearing that up, didn't know about object_id. Is this
> behaviour common in programming languages? Seems weird to me.

It's not weird if you consider :

customer0 = Customer.new("John", "Doe")
customer1 = customer0
customer0.first_name = "Paul"
puts customer1.first_name

customer0 and customer1 points to the same instance.

Java strings are misleading.


Best regards,

--
John Mettraux -///- http://jmettraux.o...

Marco Guiseppe

1/27/2007 1:40:00 AM

0

John Mettraux wrote:

>
> customer0 = Customer.new("John", "Doe")
> customer1 = customer0
> customer0.first_name = "Paul"
> puts customer1.first_name
>
> customer0 and customer1 points to the same instance.

Yes, that makes sense. I've even found a much simpler solution to my
original problem that makes the question irrelevant.

Thanks, everyone!

--
Posted via http://www.ruby-....

Damian Terentyev

1/27/2007 8:50:00 AM

0

Hi!

On Jan 27, 2007, at 04:40, Marco Guiseppe wrote:

> Yes, that makes sense. I've even found a much simpler solution to my
> original problem that makes the question irrelevant.
>
> Thanks, everyone!

I would like to notice, that if you ever need two separate objects, you
can always use a dup method, e.g:

string2 = string1.dup # Will have two different string instances

Your sincerely,
Damian/Three-eyed Fish