From: "Morris, Chris" <chris.morris@...>
Date: 2002-06-05T03:59:40+09:00
Subject: RE: When should actually freeze work ?

> 1.
> s = "abc"
> s.freeze
> s.frozen ? # >> true
> s = "123"  # doesn't throw a can't modify frozen string. why ?
> s.frozen?  # >> false (but I thought I told it to freeze :)

You're not modifying the string "abc", you're re-assigning s to a new string
altogether:

irb(main):001:0> s = "abc"
"abc"
irb(main):002:0> s.id
22437268
irb(main):004:0> s = "123"
"123"
irb(main):005:0> s.id
22408828

Try a method like reverse! on a frozen string which is self-modifying:

irb(main):007:0> s.freeze
"123"
irb(main):008:0> s.frozen?
true
irb(main):009:0> s.reverse!
TypeError: can't modify frozen string
        from (irb):9:in `reverse!'
        from (irb):9


Chris