Mastering Perl for Bioinformatics

Chapter 3. Object-Oriented Programming in Perl

In Chapter 1, you saw how modules are defined and used, and in Chapter 2, how references and data structures work. Now, it’s time to introduce the important concepts and techniques of object-oriented programming in Perl that are based on modules and references.

Object-oriented (OO) programming is one of the most important approaches to writing programs, and it is an approach that has been well supported by Perl for quite a while. Other OO languages of interest include Java, C++, and Smalltalk. Many Perl modules are written in an OO style, and their proper use requires some fundamental understanding of the OO approach. Luckily, the key concepts are fairly simple.

Perl easily supports both declarative and OO programming. (Perl was originally a declarative language only; the OO style was added fairly early on.) Declarative programming is characterized by code that declares variables and subroutines, conditional tests, if-else branches, and loops, and various arithmetic, logical, and string operators. It is up to you to manage the definition and use of the variables and subroutines so that they interact in appropriate ways. (You’ll see shortly how object-oriented programming imposes additional constraints that help you create well-behaved programs.) Many declarative programming languages are well established, including Perl and such stalwarts as C, FORTRAN, and BASIC, to name just a few. By this point, assuming you have some experience ...