From: Brian Candler <b.candler@...>
Date: 2009-11-25T03:06:52+09:00
Subject: Re: Difference between << and += for Strings and Arrays. Bug?

Pieter Hugo wrote:
> Why was it decided that '<<' should reference the original 
> object but '+' should create a new object.

Perhaps because of the way C++ uses << with streams:

  cout << "Hello world!";

> When one works with a 
> variable one shouldn't need to worry about what other stuff is being 
> modified due to a unintentional reference?

That's what mutable objects are all about. Yes, it certainly can be a 
source of bugs if you don't take care, but mutating state expected in 
OOP.

If you don't like this, you could always try Erlang instead...

> What other operators are 
> doing this? I noticed that the '.pop' array method was also modifying 
> the referenced array

Lots of operators modify the object. Look at 'ri String' and 'ri Array' 
and then check out each of the methods. Examples: String#replace, 
String#upcase!, String#chomp!

Sometimes they come in pairs which modify in-place or create a new 
object for you. For example, str.upcase is really just a shortcut for 
str.dup.upcase!
-- 
Posted via http://www.ruby-forum.com/.