From: Yohanes Santoso <ysantoso@...>
Date: 2002-12-17T06:38:42+09:00
Subject: Re: Deep copy in Rub?

"MikkelFJ" <mikkelfj-anti-spam@bigfoot.com> writes:

> clone is a flat copy.
> In Ruby, any value deep or flat, integer or complex object, is stored in an
> object as a reference.

It doesn't make sense to say a value is flat or deep.

> All references are simply copied using clone, not the content of the
> references. Not what you want.

When you do #clone, it really makes a duplicate of the object. The
difference between a 'shallow copy' versus a 'deep copy' is the extent
of the duplication. A shallow copy will only duplicate the #clone'd
object. A deep copy duplicates the #clone'd object and recursively
#clone all objects that it referes to. 

> Are you really sure you need deep copy?

There are some valid usages, a few, not many.

The easiest way to do deep copy is by using module Marshall:

require 'marshal'
a_copy = Marshal.load(Marshal.dump(the_original_object))


The pickaxe book has a more detailed documentation of this module.

YS.