Accessing Identifiers from Other Packages as Aliases

This section provides a tutorial example on how to access identifiers from another package as aliases, *identifier = *package::identifier.

As we learned earlier, to access variables from other packages is to use their fully qualified names in the format of packageName::variableName. But this format is too long, and not easy to use, see the following program:

#- CalendarTest.pl
#- Copyright (c) 1995 by Dr. Herong Yang, http://www.herongyang.com/
#
   require CalendarModule;
   print("Date: $CalendarModule::smon");
   print(" $CalendarModule::smday");
   print(" $CalendarModule::syear\n");
   print("Leap year? ",&CalendarModule::isLeapYear(), "\n");
   exit;

To make this easier, variables from other packages can be introduced into the current package as aliases. Here is how I improved the previous program:

#- CalendarAliasTest.pl
#- Copyright (c) 1999 by Dr. Herong Yang, http://www.herongyang.com/
#
   require CalendarModule;
   *smon = *CalendarModule::smon;
   *smday = *CalendarModule::smday;
   *syear = *CalendarModule::syear;
   *isLeapYear = *CalendarModule::isLeapYear;
   print("Date: $smon");
   print(" $smday");
   print(" $syear\n");
   print("Leap year? ",&isLeapYear(), "\n");
   exit;

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

 Symbolic (or Soft) References

 Hard References - Addresses of Memory Objects

 Objects (or References) and Classes (or Packages)

Typeglob and Importing Identifiers from Other Packages

 Typeglob, Symbolic Table and Identifier Aliases

Accessing Identifiers from Other Packages as Aliases

 Exporting and Importing Package Identifiers

 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