Defining Your Own Perl Module

This section provides a tutorial example on how to define your own Perl module with its own name space and stored in a separate script file named as *.pm.

Perl Module - A special source code file that:

Here is a dummy example of Perl module, MyModule.pm,

#- MyModule.pm
#- Copyright (c) 1995 by Dr. Herong Yang, http://www.herongyang.com/
#
   package MyModule;
   sub BEGIN {
      print("Printing in BEGIN of ",__PACKAGE__,"...\n");
      $begin = "Begin";
   }   	
   sub CHECK {
      print("Printing in CHECK of ",__PACKAGE__,"...\n");
      $check = "Check";
   }   	
   sub INIT {
      print("Printing in INIT of ",__PACKAGE__,"...\n");
      $init = "Init";
   }
   sub END {
      print("Printing in END of ",__PACKAGE__,"...\n");
      $end = "End";
   }
   print("Printing from MyModule.pm...\n");
sub myModuleSub {
   print("Printing from myModuleSub()...\n");
}
1;   

And a dummy test script, ModuleTest.pl,

#- ModuleTest.pl
#- Copyright (c) 1995 by Dr. Herong Yang, http://www.herongyang.com/
#
   print("Printing from ModuleTest.pl before MyModule...\n");
   require MyModule;
   print("Printing from ModuleTest.pl after MyModule...\n");
   print("MyModule::begin = $MyModule::begin\n");
   print("MyModule::check = $MyModule::check\n");
   print("MyModule::init = $MyModule::init\n");
   print("MyModule::end = $MyModule::end\n");
   &MyModule::myModuleSub();
   exit;

Here is the output of the test script:

Printing from ModuleTest.pl before MyModule...
Printing in BEGIN of MyModule...
Printing from MyModule.pm...
Printing from ModuleTest.pl after MyModule...
MyModule::begin = Begin
MyModule::check =
MyModule::init =
MyModule::end =
Printing from myModuleSub()...
Printing in END of MyModule...

A couple of notes here:

Table of Contents

 About This Book

 Perl on Linux Systems

 ActivePerl on Windows Systems

 Data Types: Values and Variables

 Expressions, Operations and Simple Statements

 User Defined Subroutines

 Perl Built-in Debugger

Name Spaces and Perl Module Files

 Including Script Codes from Other Files

 do() Function - Including Script Files

 require() Function - Including Script Files

 "package" Statement - Switching Name Space

 BEGIN(), CHECK(), INIT() and END() Functions

Defining Your Own Perl Module

 CalendarModule.pm - A Sample Perl Module

 Symbolic (or Soft) References

 Hard References - Addresses of Memory Objects

 Objects (or References) and Classes (or Packages)

 Typeglob and Importing Identifiers from Other Packages

 String Built-in Functions and Performance

 File Handles and Data Input/Output

 Open Files in Binary Mode

 Open Directories and Read File Names

 File System Functions and Operations

 Converting Perl Script to Executable Binary

 Using DBM Database Files

 Using MySQL Database Server

 Socket Communication Over the Internet

 XML::Simple Module - XML Parser and Generator

 XML Communication Model

 SOAP::Lite - SOAP Server-Client Communication Module

 Perl Programs as IIS Server CGI Scripts

 CGI (Common Gateway Interface)

 XML-RPC - Remote Procedure Call with XML and HTTP

 RPC::XML - Perl Implementation of XML-RPC

 Integrating Perl with Apache Web Server

 CGI.pm Module for Building Web Pages

 LWP::UserAgent and Web Site Testing

 References

 PDF Printing Version