Chapter 2

log file as well as the functions needed to operate on this state data. This is the 

basic definition of an object: state data and functions to operate on that state 

wrapped up in one data structure. The benefits of object orientation are increased 

flexibility and improved potential for code reuse.

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References: A Brief Refresher

Perl supports object oriented programming through references. It's possible to do 

a lot of useful things with Perl without using a single reference. As a result you 

may be ready to learn object oriented Perl without having ever used a single ref 

erence. I'll give you a quick refresher on the topic, but if you're left with questions, 

I suggest you head for a good introductory book on Perl for details.

A reference is simply a variable that points to another variable. By points to, I 

mean that you can follow the link from a reference to the variable it references. 

This action of following a reference is known as dereferencing.

Here's a simple example that prints  Hello, New World  using a reference to a scalar:

$message = "Hello, New World.\n";

$ref = \$message;

print $$ref;

This example shows two important operations on references. First, a reference is 

created using the \ operator:

$ref = \$message;

After this line, $ref points to $message. You can see this in action by changing 

$message and observing that the new value is visible through $ref:

$message = "Goodbye, dear friend.";

print $$ref; # prints "Goodbye, dear friend."

Second, the reference is dereferenced using a second $ in front of the reference:

print $$ref;

You can create a reference to other types of variables but the result is always 

stored in a scalar. For example, this example prints  Hello, New World  using a 

reference to an array:

@array = ("Hello,", "New", "World");

$ref = \@array;

print join(" ", @$ref) . "\n";

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