CONTENTS

• NAME
• THE PERL MODULE LIBRARY
  • Pragmatic Modules
  • Standard Modules
  • Extension Modules
• CPAN
• Modules: Creation, Use, and Abuse
  • Guidelines for Module Creation
  • Guidelines for Converting Perl 4 Library Scripts into Modules
  • Guidelines for Reusing Application Code
• NOTE

#NAME

perlmodlib - constructing new Perl modules and finding existing ones

#THE PERL MODULE LIBRARY

Many modules are included in the Perl distribution. These are described below, and all end in .pm. You may discover compiled library files (usually ending in .so) or small pieces of modules to be autoloaded (ending in .al); these were automatically generated by the installation process. You may also discover files in the library directory that end in either .pl or .ph. These are old libraries supplied so that old programs that use them still run. The .pl files will all eventually be converted into standard modules, and the .ph files made by h2ph will probably end up as extension modules made by h2xs. (Some .ph values may already be available through the POSIX, Errno, or Fcntl modules.) The pl2pm file in the distribution may help in your conversion, but it's just a mechanical process and therefore far from bulletproof.

#Pragmatic Modules

They work somewhat like compiler directives (pragmata) in that they tend to affect the compilation of your program, and thus will usually work well only when used within a use, or no. Most of these are lexically scoped, so an inner BLOCK may countermand them by saying:

no integer;
no strict 'refs';
no warnings;

which lasts until the end of that BLOCK.

Some pragmas are lexically scoped--typically those that affect the $^H hints variable. Others affect the current package instead, like use vars and use subs, which allow you to predeclare a variables or subroutines within a particular file rather than just a block. Such declarations are effective for the entire file for which they were declared. You cannot rescind them with no vars or no subs.

The following pragmas are defined (and have their own documentation).

#attributes

Get/set subroutine or variable attributes

#autodie

Replace functions with ones that succeed or die with lexical scope

#autodie::exception

Exceptions from autodying functions.

#autodie::exception::system

Exceptions from autodying system().

#autodie::hints

Provide hints about user subroutines to autodie

#autodie::skip

Skip a package when throwing autodie exceptions

#autouse

Postpone load of modules until a function is used

#base

Establish an ISA relationship with base classes at compile time

#bigfloat

Transparent big floating point number support for Perl

#bigint

Transparent big integer support for Perl

#bignum

Transparent big number support for Perl

#bigrat

Transparent big rational number support for Perl

#blib

Use MakeMaker's uninstalled version of a package

#builtin

Import built-in utility functions

#bytes

Expose the individual bytes of characters

#charnames

Access to Unicode character names and named character sequences; also define character names

#constant

Declare constants

#deprecate

Perl pragma for deprecating the inclusion of a module in core

#diagnostics

Produce verbose warning diagnostics

#encoding

Allows you to write your script in non-ASCII and non-UTF-8

#encoding::warnings

Warn on implicit encoding conversions

#experimental

Experimental features made easy

#feature

Enable new features

#fields

Compile-time class fields

#filetest

Control the filetest permission operators

#if

use a Perl module if a condition holds

#integer

Use integer arithmetic instead of floating point

#less

Request less of something

#lib

Manipulate @INC at compile time

#locale

Use or avoid POSIX locales for built-in operations

#mro

Method Resolution Order

#ok

Alternative to Test::More::use_ok

#open

Set default PerlIO layers for input and output

#ops

Restrict unsafe operations when compiling

#overload

Package for overloading Perl operations

#overloading

Lexically control overloading

#parent

Establish an ISA relationship with base classes at compile time

#re

Alter regular expression behaviour

#sigtrap

Enable simple signal handling

#sort

Control sort() behaviour

#strict

Restrict unsafe constructs

#subs

Predeclare subroutine names

#threads

Perl interpreter-based threads

#threads::shared

Perl extension for sharing data structures between threads

#utf8

Enable/disable UTF-8 (or UTF-EBCDIC) in source code

#vars

Predeclare global variable names

#version

Perl extension for Version Objects

#vmsish

Control VMS-specific language features

#warnings

Control optional warnings

#warnings::register

Warnings import function

#Standard Modules

Standard, bundled modules are all expected to behave in a well-defined manner with respect to namespace pollution because they use the Exporter module. See their own documentation for details.

It's possible that not all modules listed below are installed on your system. For example, the GDBM_File module will not be installed if you don't have the gdbm library.

#Amiga::ARexx

Perl extension for ARexx support

#Amiga::Exec

Perl extension for low level amiga support

#AnyDBM_File

Provide framework for multiple DBMs

#App::Cpan

Easily interact with CPAN from the command line

#App::Prove

Implements the prove command.

#App::Prove::State

State storage for the prove command.

#App::Prove::State::Result

Individual test suite results.

#App::Prove::State::Result::Test

Individual test results.

#Archive::Tar

Module for manipulations of tar archives

#Archive::Tar::File

A subclass for in-memory extracted file from Archive::Tar

#Attribute::Handlers

Simpler definition of attribute handlers

#AutoLoader

Load subroutines only on demand

#AutoSplit

Split a package for autoloading

#B

The Perl Compiler Backend

#B::Concise

Walk Perl syntax tree, printing concise info about ops

#B::Deparse

Perl compiler backend to produce perl code

#B::Op_private

OP op_private flag definitions

#B::Showlex

Show lexical variables used in functions or files

#B::Terse

Walk Perl syntax tree, printing terse info about ops

#B::Xref

Generates cross reference reports for Perl programs

#Benchmark

Benchmark running times of Perl code

#IO::Socket::IP

Family-neutral IP socket supporting both IPv4 and IPv6

#Socket

Networking constants and support functions

#CORE

Namespace for Perl's core routines

#CPAN

Query, download and build perl modules from CPAN sites

#CPAN::API::HOWTO

A recipe book for programming with CPAN.pm

#CPAN::Debug

Internal debugging for CPAN.pm

#CPAN::Distroprefs

Read and match distroprefs

#CPAN::FirstTime

Utility for CPAN::Config file Initialization

#CPAN::HandleConfig

Internal configuration handling for CPAN.pm

#CPAN::Kwalify

Interface between CPAN.pm and Kwalify.pm

#CPAN::Meta

The distribution metadata for a CPAN dist

#CPAN::Meta::Converter

Convert CPAN distribution metadata structures

#CPAN::Meta::Feature

An optional feature provided by a CPAN distribution

#CPAN::Meta::History

History of CPAN Meta Spec changes

#CPAN::Meta::History::Meta_1_0

Version 1.0 metadata specification for META.yml

#CPAN::Meta::History::Meta_1_1

Version 1.1 metadata specification for META.yml

#CPAN::Meta::History::Meta_1_2

Version 1.2 metadata specification for META.yml

#CPAN::Meta::History::Meta_1_3

Version 1.3 metadata specification for META.yml

#CPAN::Meta::History::Meta_1_4

Version 1.4 metadata specification for META.yml

#CPAN::Meta::Merge

Merging CPAN Meta fragments

#CPAN::Meta::Prereqs

A set of distribution prerequisites by phase and type

#CPAN::Meta::Requirements

A set of version requirements for a CPAN dist

#CPAN::Meta::Spec

Specification for CPAN distribution metadata

#CPAN::Meta::Validator

Validate CPAN distribution metadata structures

#CPAN::Meta::YAML

Read and write a subset of YAML for CPAN Meta files

#CPAN::Nox

Wrapper around CPAN.pm without using any XS module

#CPAN::Plugin

Base class for CPAN shell extensions

#CPAN::Plugin::Specfile

Proof of concept implementation of a trivial CPAN::Plugin

#CPAN::Queue

Internal queue support for CPAN.pm

#CPAN::Tarzip

Internal handling of tar archives for CPAN.pm

#CPAN::Version

Utility functions to compare CPAN versions

#Carp

Alternative warn and die for modules

#Class::Struct

Declare struct-like datatypes as Perl classes

#Compress::Raw::Bzip2

Low-Level Interface to bzip2 compression library

#Compress::Raw::Zlib

Low-Level Interface to zlib compression library

#Compress::Zlib

Interface to zlib compression library

#Config

Access Perl configuration information

#Config::Extensions

Hash lookup of which core extensions were built.

#Config::Perl::V

Structured data retrieval of perl -V output

#Cwd

Get pathname of current working directory

#DB

Programmatic interface to the Perl debugging API

#DBM_Filter

Filter DBM keys/values

#DBM_Filter::compress

Filter for DBM_Filter

#DBM_Filter::encode

Filter for DBM_Filter

#DBM_Filter::int32

Filter for DBM_Filter

#DBM_Filter::null

Filter for DBM_Filter

#DBM_Filter::utf8

Filter for DBM_Filter

#DB_File

Perl5 access to Berkeley DB version 1.x

#Data::Dumper

Stringified perl data structures, suitable for both printing and eval

#Devel::PPPort

Perl/Pollution/Portability

#Devel::Peek

A data debugging tool for the XS programmer

#Devel::SelfStubber

Generate stubs for a SelfLoading module

#Digest

Modules that calculate message digests

#Digest::MD5

Perl interface to the MD5 Algorithm

#Digest::SHA

Perl extension for SHA-1/224/256/384/512

#Digest::base

Digest base class

#Digest::file

Calculate digests of files

#DirHandle

(obsolete) supply object methods for directory handles

#Dumpvalue

Provides screen dump of Perl data.

#DynaLoader

Dynamically load C libraries into Perl code

#Encode

Character encodings in Perl

#Encode::Alias

Alias definitions to encodings

#Encode::Byte

Single Byte Encodings

#Encode::CJKConstants

Internally used by Encode::??::ISO_2022_*

#Encode::CN

China-based Chinese Encodings

#Encode::CN::HZ

Internally used by Encode::CN

#Encode::Config

Internally used by Encode

#Encode::EBCDIC

EBCDIC Encodings

#Encode::Encoder

Object Oriented Encoder

#Encode::Encoding

Encode Implementation Base Class

#Encode::GSM0338

ETSI GSM 03.38 Encoding

#Encode::Guess

Guesses encoding from data

#Encode::JP

Japanese Encodings

#Encode::JP::H2Z

Internally used by Encode::JP::2022_JP*

#Encode::JP::JIS7

Internally used by Encode::JP

#Encode::KR

Korean Encodings

#Encode::KR::2022_KR

Internally used by Encode::KR

#Encode::MIME::Header

MIME encoding for an unstructured email header

#Encode::MIME::Name

Internally used by Encode

#Encode::PerlIO

A detailed document on Encode and PerlIO

#Encode::Supported

Encodings supported by Encode

#Encode::Symbol

Symbol Encodings

#Encode::TW

Taiwan-based Chinese Encodings

#Encode::Unicode

Various Unicode Transformation Formats

#Encode::Unicode::UTF7

UTF-7 encoding

#English

Use nice English (or awk) names for ugly punctuation variables

#Env

Perl module that imports environment variables as scalars or arrays

#Errno

System errno constants

#Exporter

Implements default import method for modules

#Exporter::Heavy

Exporter guts

#ExtUtils::CBuilder

Compile and link C code for Perl modules

#ExtUtils::CBuilder::Platform::Windows

Builder class for Windows platforms

#ExtUtils::Command

Utilities to replace common UNIX commands in Makefiles etc.

#ExtUtils::Command::MM

Commands for the MM's to use in Makefiles

#ExtUtils::Constant

Generate XS code to import C header constants

#ExtUtils::Constant::Base

Base class for ExtUtils::Constant objects

#ExtUtils::Constant::Utils

Helper functions for ExtUtils::Constant

#ExtUtils::Constant::XS

Generate C code for XS modules' constants.

#ExtUtils::Embed

Utilities for embedding Perl in C/C++ applications

#ExtUtils::Install

Install files from here to there

#ExtUtils::Installed

Inventory management of installed modules

#ExtUtils::Liblist

Determine libraries to use and how to use them

#ExtUtils::MM

OS adjusted ExtUtils::MakeMaker subclass

#ExtUtils::MM_AIX

AIX specific subclass of ExtUtils::MM_Unix

#ExtUtils::MM_Any

Platform-agnostic MM methods

#ExtUtils::MM_BeOS

Methods to override UN*X behaviour in ExtUtils::MakeMaker

#ExtUtils::MM_Cygwin

Methods to override UN*X behaviour in ExtUtils::MakeMaker

#ExtUtils::MM_DOS

DOS specific subclass of ExtUtils::MM_Unix

#ExtUtils::MM_Darwin

Special behaviors for OS X

#ExtUtils::MM_MacOS

Once produced Makefiles for MacOS Classic

#ExtUtils::MM_NW5

Methods to override UN*X behaviour in ExtUtils::MakeMaker

#ExtUtils::MM_OS2

Methods to override UN*X behaviour in ExtUtils::MakeMaker

#ExtUtils::MM_OS390

OS390 specific subclass of ExtUtils::MM_Unix

#ExtUtils::MM_QNX

QNX specific subclass of ExtUtils::MM_Unix

#ExtUtils::MM_UWIN

U/WIN specific subclass of ExtUtils::MM_Unix

#ExtUtils::MM_Unix

Methods used by ExtUtils::MakeMaker

#ExtUtils::MM_VMS

Methods to override UN*X behaviour in ExtUtils::MakeMaker

#ExtUtils::MM_VOS

VOS specific subclass of ExtUtils::MM_Unix

#ExtUtils::MM_Win32

Methods to override UN*X behaviour in ExtUtils::MakeMaker

#ExtUtils::MM_Win95

Method to customize MakeMaker for Win9X

#ExtUtils::MY

ExtUtils::MakeMaker subclass for customization

#ExtUtils::MakeMaker

Create a module Makefile

#ExtUtils::MakeMaker::Config

Wrapper around Config.pm

#ExtUtils::MakeMaker::FAQ

Frequently Asked Questions About MakeMaker

#ExtUtils::MakeMaker::Locale

Bundled Encode::Locale

#ExtUtils::MakeMaker::Tutorial

Writing a module with MakeMaker

#ExtUtils::Manifest

Utilities to write and check a MANIFEST file

#ExtUtils::Miniperl

Write the C code for miniperlmain.c and perlmain.c

#ExtUtils::Mkbootstrap

Make a bootstrap file for use by DynaLoader

#ExtUtils::Mksymlists

Write linker options files for dynamic extension

#ExtUtils::PL2Bat

Batch file creation to run perl scripts on Windows

#