From: Stefano Crocco <stefano.crocco@...>
Date: 2007-02-22T03:17:19+09:00
Subject: Re: weird thing with gsub!

Alle mercoled� 21 febbraio 2007, niceview ha scritto:
> I'd like to show you some example.
>
> --
>
> def t1(str)
>   str = str.gsub(/1/, "!")
> end
>
> def t2(str)
>   str.gsub!(/1/, "!")
> end
>
> a = "123"
> p t1(a)   # => "!23"
> p a       # => "123"
>
> a = "123"
> p t2(a)   # => "!23"
> p a       # => "!23"
>
> --
>
> Is 'str' variable a local variable in 't2' method?
>
> Why 'str.gsub!(/1/, "!")' change 'a' variable?

Because gsub! changes its argument. While str is a local variable in t2, the 
object it references is the same that a references. You can see this adding 
the line 

puts str.object_id

in the definition of t2 and the line

puts a.object_id

after a='123'.  You'll see that str and a are the same thing.

I hope this helps

Stefano