From: Serabe <serabe@...>
Date: 2008-07-13T04:12:29+09:00
Subject: Re: behavior of delete! method

2008/7/12 Alex DeCaria <alex.decaria@...>:
> I am confused by the use of the delete! method as applied to a string.
> In IRB if I type
>
> foo = "hello"

This creates the object "hello" of type String and foo points to it.

> bar = foo

Now bar points to the same "hello" object. (Type 'bar.object_id' and
'foo.object_id' to see they have the same id).

> foo.delete!("h")

Now, the "hello" object is modified, so foo and bar point to the
modified "ello" object.

> then both foo and bar become "ello".  How come bar isn't independent of
> foo in this case?

For making bar independent of foo, you should do 'bar = foo.clone'
(check the object_id and you'll see the change).

> If I then type
>
> foo = foo + "oo"
>
> then only foo becomes "ellooo" while bar remains "ello"
>
> Why is bar independent of foo in the second case, but not the first?

Because now, you're making foo point to a new object and not changing
the object.

In general, the methods whose name ends in ! do change the object.

Regards,

Serabe

> Thanks,
>
> Alex
> --
> Posted via http://www.ruby-forum.com/.
>
>



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