CHAPTER 2

Perl Module Basics

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PAGHETTI CODE

 if you don't know what it means, you're probably writing it. 

Spaghetti code gets its name from the numerous and thoroughly knotted paths 

your program takes through its source code. In the classic case, every subroutine 

in the program will call every other subroutine at least once (if there are subrou 

tines goto is marinara for spaghetti code). Nothing is commented, or if it is, then 

the comments are misleading. Executable code is mixed in with subroutine decla 

rations at random. Basically, it's your worst nightmare.

What makes spaghetti code so bad is that even a small change in one part 

of the program can have dire consequences in an unrelated area. Fixing bugs 

becomes a dangerous activity find one, and two more spring from the mist. Code 

like this invariably gets rewritten rather than enhanced, at tremendous expense.

To combat spaghetti code, you need modular programming. Modular pro 

gramming is the practice of breaking a large program into smaller pieces called 

modules. Each module offers its service through a well documented interface. The 

internals of the module are considered private, or encapsulated.

The beauty of modular programming is that the internals of the module can 

change without affecting code that uses the module. Fixing bugs is usually just a 

matter of finding the offending code and making sure that the fix doesn't affect the 

interface. Furthermore, modular programming makes your job easier; you only 

need to worry about the implementation of a single module at a time, rather than 

an entire complex program.

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