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 byh2ph will probably end up as extension modules made byh2xs. (Some.ph values may already be available through the POSIX, Errno, or Fcntl modules.) Thepl2pm 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 ause, orno. 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, likeuse vars anduse subs, which allow you to predeclare a variables or subroutines within a particularfile rather than just a block. Such declarations are effective for the entire file for which they were declared. You cannot rescind them withno vars orno 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

#source::encoding

Declare Perl source code encoding

#stable

Experimental features made easy, once we know they're stable

#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 theprove command.

#App::Prove::State

State storage for theprove 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

#Test2::Tools::Refcount

Assert reference counts on objects

#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::Requirements::Range

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 or zlib-ng 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 andeval

#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

#ExtUtils::Packlist

Manage .packlist files

#ExtUtils::ParseXS

Converts Perl XS code into C code

#ExtUtils::ParseXS::Constants

Initialization values for some globals

#ExtUtils::ParseXS::Eval

Clean package to evaluate code in

#ExtUtils::ParseXS::Utilities

Subroutines used with ExtUtils::ParseXS

#ExtUtils::Typemaps

Read/Write/Modify Perl/XS typemap files

#ExtUtils::Typemaps::Cmd

Quick commands for handling typemaps

#ExtUtils::Typemaps::InputMap

Entry in the INPUT section of a typemap

#ExtUtils::Typemaps::OutputMap

Entry in the OUTPUT section of a typemap

#ExtUtils::Typemaps::Type

Entry in the TYPEMAP section of a typemap

#ExtUtils::XSSymSet

Keep sets of symbol names palatable to the VMS linker

#ExtUtils::testlib

Add blib/* directories to @INC

#Fatal

Replace functions with equivalents which succeed or die

#Fcntl

Various flag constants and helper functions from C's fcntl.h

#File::Basename

Parse file paths into directory, filename and suffix.

#File::Compare

Compare files or filehandles

#File::Copy

Copy files or filehandles

#File::DosGlob

DOS like globbing and then some

#File::Fetch

A generic file fetching mechanism

#File::Find

Traverse a directory tree.

#File::Glob

Perl extension for BSD glob routine

#File::GlobMapper

Extend File Glob to Allow Input and Output Files

#File::Path

Create or remove directory trees

#File::Spec

Portably perform operations on file names

#File::Spec::AmigaOS

File::Spec for AmigaOS

#File::Spec::Cygwin

Methods for Cygwin file specs

#File::Spec::Epoc

Methods for Epoc file specs

#File::Spec::Functions

Portably perform operations on file names

#File::Spec::Mac

File::Spec for Mac OS (Classic)

#File::Spec::OS2

Methods for OS/2 file specs

#File::Spec::Unix

File::Spec for Unix, base for other File::Spec modules

#File::Spec::VMS

Methods for VMS file specs

#File::Spec::Win32

Methods for Win32 file specs

#File::Temp

Return name and handle of a temporary file safely

#File::stat

By-name interface to Perl's built-in stat() functions

#FileCache

Keep more files open than the system permits

#FileHandle

Supply object methods for filehandles

#Filter::Simple

Simplified source filtering

#Filter::Util::Call

Perl Source Filter Utility Module

#FindBin

Locate directory of original Perl script

#GDBM_File

Perl5 access to the gdbm library.

#Getopt::Long

Extended processing of command line options

#Getopt::Long::Parser

Getopt::Long object-oriented interface

#Getopt::Std

Process single-character switches with switch clustering

#HTTP::Tiny

A small, simple, correct HTTP/1.1 client

#Hash::Util

A selection of general-utility hash subroutines

#Hash::Util::FieldHash

Support for Inside-Out Classes

#I18N::Collate

Compare 8-bit scalar data according to the current locale

#I18N::LangTags

Functions for dealing with RFC3066-style language tags

#I18N::LangTags::Detect

Detect the user's language preferences

#I18N::LangTags::List

Tags and names for human languages

#I18N::Langinfo

Query locale information

#IO

Load various IO modules

#IO::Compress::Base

Base Class for IO::Compress modules

#IO::Compress::Bzip2

Write bzip2 files/buffers

#IO::Compress::Deflate

Write RFC 1950 files/buffers

#IO::Compress::FAQ

Frequently Asked Questions about IO::Compress

#IO::Compress::Gzip

Write RFC 1952 files/buffers

#IO::Compress::RawDeflate

Write RFC 1951 files/buffers

#IO::Compress::Zip

Write zip files/buffers

#IO::Dir

Supply object methods for directory handles

#IO::File

Supply object methods for filehandles

#IO::Handle

Supply object methods for I/O handles

#IO::Pipe

Supply object methods for pipes

#IO::Poll

Object interface to system poll call

#IO::Seekable

Supply seek based methods for I/O objects

#IO::Select

OO interface to theselect system call

#IO::Socket

Object interface to socket communications

#IO::Socket::INET

Object interface for AF_INET domain sockets

#IO::Socket::UNIX

Object interface for AF_UNIX domain sockets

#IO::Uncompress::AnyInflate

Uncompress zlib-based (zip, gzip) file/buffer

#IO::Uncompress::AnyUncompress

Uncompress gzip, zip, bzip2, zstd, xz, lzma, lzip, lzf or lzop file/buffer

#IO::Uncompress::Base

Base Class for IO::Uncompress modules

#IO::Uncompress::Bunzip2

Read bzip2 files/buffers

#IO::Uncompress::Gunzip

Read RFC 1952 files/buffers

#IO::Uncompress::Inflate

Read RFC 1950 files/buffers

#IO::Uncompress::RawInflate

Read RFC 1951 files/buffers

#IO::Uncompress::Unzip

Read zip files/buffers

#IO::Zlib

IO:: style interface toCompress::Zlib

#IPC::Cmd

Finding and running system commands made easy

#IPC::Msg

SysV Msg IPC object class

#IPC::Open2

Open a process for both reading and writing using open2()

#IPC::Open3

Open a process for reading, writing, and error handling using open3()

#IPC::Semaphore

SysV Semaphore IPC object class

#IPC::SharedMem

SysV Shared Memory IPC object class

#IPC::SysV

System V IPC constants and system calls

#Internals

Reserved special namespace for internals related functions

#JSON::PP

JSON::XS compatible pure-Perl module.

#JSON::PP::Boolean

Dummy module providing JSON::PP::Boolean

#List::Util

A selection of general-utility list subroutines

#List::Util::XS

Indicate if List::Util was compiled with a C compiler

#Locale::Maketext

Framework for localization

#Locale::Maketext::Cookbook

Recipes for using Locale::Maketext

#Locale::Maketext::Guts

Deprecated module to load Locale::Maketext utf8 code

#Locale::Maketext::GutsLoader

Deprecated module to load Locale::Maketext utf8 code

#Locale::Maketext::Simple

Simple interface to Locale::Maketext::Lexicon

#Locale::Maketext::TPJ13

Article about software localization

#MIME::Base64

Encoding and decoding of base64 strings

#MIME::QuotedPrint

Encoding and decoding of quoted-printable strings

#Math::BigFloat

Arbitrary size floating point math package

#Math::BigInt

Arbitrary size integer math package

#Math::BigInt::Calc

Pure Perl module to support Math::BigInt

#Math::BigInt::FastCalc

Math::BigInt::Calc with some XS for more speed

#Math::BigInt::Lib

Virtual parent class for Math::BigInt libraries

#Math::BigRat

Arbitrary size rational number math package

#Math::Complex

Complex numbers and associated mathematical functions

#Math::Trig

Trigonometric functions

#Memoize

Make functions faster by trading space for time

#Memoize::AnyDBM_File

Glue to provide EXISTS for AnyDBM_File for Storable use

#Memoize::Expire

Plug-in module for automatic expiration of memoized values

#Memoize::NDBM_File

Glue to provide EXISTS for NDBM_File for Storable use

#Memoize::SDBM_File

DEPRECATED compability shim

#Memoize::Storable

Store Memoized data in Storable database

#Module::CoreList

What modules shipped with versions of perl

#Module::CoreList::Utils

What utilities shipped with versions of perl

#Module::Load

Runtime require of both modules and files

#Module::Load::Conditional

Looking up module information / loading at runtime

#Module::Loaded

Mark modules as loaded or unloaded

#Module::Metadata

Gather package and POD information from perl module files

#NDBM_File

Tied access to ndbm files

#NEXT

Provide a pseudo-class NEXT (et al) that allows method redispatch

#Net::Cmd

Network Command class (as used by FTP, SMTP etc)

#Net::Config

Local configuration data for libnet

#Net::Domain

Attempt to evaluate the current host's internet name and domain

#Net::FTP

FTP Client class

#Net::FTP::dataconn

FTP Client data connection class

#Net::NNTP

NNTP Client class

#Net::Netrc

OO interface to users netrc file

#Net::POP3

Post Office Protocol 3 Client class (RFC1939)

#Net::Ping

Check a remote host for reachability

#Net::SMTP

Simple Mail Transfer Protocol Client

#Net::Time

Time and daytime network client interface

#Net::hostent

By-name interface to Perl's built-in gethost*() functions

#Net::libnetFAQ

Libnet Frequently Asked Questions

#Net::netent

By-name interface to Perl's built-in getnet*() functions

#Net::protoent

By-name interface to Perl's built-in getproto*() functions

#Net::servent

By-name interface to Perl's built-in getserv*() functions

#O

Generic interface to Perl Compiler backends

#ODBM_File

Tied access to odbm files

#Opcode

Disable named opcodes when compiling perl code

#POSIX

Perl interface to IEEE Std 1003.1

#Params::Check

A generic input parsing/checking mechanism.

#Parse::CPAN::Meta

Parse META.yml and META.json CPAN metadata files

#Perl::OSType

Map Perl operating system names to generic types

#PerlIO

On demand loader for PerlIO layers and root of PerlIO::* name space

#PerlIO::encoding

Encoding layer

#PerlIO::mmap

Memory mapped IO

#PerlIO::scalar

In-memory IO, scalar IO

#PerlIO::via

Helper class for PerlIO layers implemented in perl

#PerlIO::via::QuotedPrint

PerlIO layer for quoted-printable strings

#Pod::Checker

Check pod documents for syntax errors

#Pod::Escapes

For resolving Pod E<...> sequences

#Pod::Functions

Group Perl's functions a la perlfunc.pod

#Pod::Html

Module to convert pod files to HTML

#Pod::Html::Util

Helper functions for Pod-Html

#Pod::Man

Convert POD data to formatted *roff input

#Pod::ParseLink

Parse an L<> formatting code in POD text

#Pod::Perldoc

Look up Perl documentation in Pod format.

#Pod::Perldoc::BaseTo

Base for Pod::Perldoc formatters

#Pod::Perldoc::GetOptsOO

Customized option parser for Pod::Perldoc

#Pod::Perldoc::ToANSI

Render Pod with ANSI color escapes

#Pod::Perldoc::ToChecker

Let Perldoc check Pod for errors

#Pod::Perldoc::ToMan

Let Perldoc render Pod as man pages

#Pod::Perldoc::ToNroff

Let Perldoc convert Pod to nroff

#Pod::Perldoc::ToPod

Let Perldoc render Pod as ... Pod!

#Pod::Perldoc::ToRtf

Let Perldoc render Pod as RTF

#Pod::Perldoc::ToTerm

Render Pod with terminal escapes

#Pod::Perldoc::ToText

Let Perldoc render Pod as plaintext

#Pod::Perldoc::ToTk

Let Perldoc use Tk::Pod to render Pod

#Pod::Perldoc::ToXml

Let Perldoc render Pod as XML

#Pod::Simple

Framework for parsing Pod

#Pod::Simple::Checker

Check the Pod syntax of a document

#Pod::Simple::Debug

Put Pod::Simple into trace/debug mode

#Pod::Simple::DumpAsText

Dump Pod-parsing events as text

#Pod::Simple::DumpAsXML

Turn Pod into XML

#Pod::Simple::HTML

Convert Pod to HTML

#Pod::Simple::HTMLBatch

Convert several Pod files to several HTML files

#Pod::Simple::JustPod

Just the Pod, the whole Pod, and nothing but the Pod

#Pod::Simple::LinkSection

Represent "section" attributes of L codes

#Pod::Simple::Methody

Turn Pod::Simple events into method calls

#Pod::Simple::PullParser

A pull-parser interface to parsing Pod

#Pod::Simple::PullParserEndToken

End-tokens from Pod::Simple::PullParser

#Pod::Simple::PullParserStartToken

Start-tokens from Pod::Simple::PullParser

#Pod::Simple::PullParserTextToken

Text-tokens from Pod::Simple::PullParser

#Pod::Simple::PullParserToken

Tokens from Pod::Simple::PullParser

#Pod::Simple::RTF

Format Pod as RTF

#Pod::Simple::Search

Find POD documents in directory trees

#Pod::Simple::SimpleTree

Parse Pod into a simple parse tree

#Pod::Simple::Subclassing

Write a formatter as a Pod::Simple subclass

#Pod::Simple::Text

Format Pod as plaintext

#Pod::Simple::TextContent

Get the text content of Pod

#Pod::Simple::XHTML

Format Pod as validating XHTML

#Pod::Simple::XMLOutStream

Turn Pod into XML

#Pod::Text

Convert POD data to formatted text

#Pod::Text::Color

Convert POD data to formatted color ASCII text

#Pod::Text::Overstrike

Convert POD data to formatted overstrike text

#Pod::Text::Termcap

Convert POD data to ASCII text with format escapes

#Pod::Usage

Extracts POD documentation and shows usage information

#SDBM_File

Tied access to sdbm files

#Safe

Compile and execute code in restricted compartments

#Scalar::Util

A selection of general-utility scalar subroutines

#Search::Dict

Look - search for key in dictionary file

#SelectSaver

Save and restore selected file handle

#SelfLoader

Load functions only on demand

#Storable

Persistence for Perl data structures

#Sub::Util

A selection of utility subroutines for subs and CODE references

#Symbol

Manipulate Perl symbols and their names

#Sys::Hostname

Try every conceivable way to get hostname

#Sys::Syslog

Perl interface to the UNIX syslog(3) calls

#Sys::Syslog::Win32

Win32 support for Sys::Syslog

#TAP::Base

Base class that provides common functionality toTAP::Parser

#TAP::Formatter::Base

Base class for harness output delegates

#TAP::Formatter::Color

Run Perl test scripts with color

#TAP::Formatter::Console

Harness output delegate for default console output

#TAP::Formatter::Console::ParallelSession

Harness output delegate for parallel console output

#TAP::Formatter::Console::Session

Harness output delegate for default console output

#TAP::Formatter::File

Harness output delegate for file output

#TAP::Formatter::File::Session

Harness output delegate for file output

#TAP::Formatter::Session

Abstract base class for harness output delegate

#TAP::Harness

Run test scripts with statistics

#TAP::Harness::Env

Parsing harness related environmental variables where appropriate

#TAP::Object

Base class that provides common functionality to allTAP::* modules

#TAP::Parser

ParseTAP output

#TAP::Parser::Aggregator

Aggregate TAP::Parser results

#TAP::Parser::Grammar

A grammar for the Test Anything Protocol.

#TAP::Parser::Iterator

Base class for TAP source iterators

#TAP::Parser::Iterator::Array

Iterator for array-based TAP sources

#TAP::Parser::Iterator::Process

Iterator for process-based TAP sources

#TAP::Parser::Iterator::Stream

Iterator for filehandle-based TAP sources

#TAP::Parser::IteratorFactory

Figures out which SourceHandler objects to use for a given Source

#TAP::Parser::Multiplexer

Multiplex multiple TAP::Parsers

#TAP::Parser::Result

Base class for TAP::Parser output objects

#TAP::Parser::Result::Bailout

Bailout result token.

#TAP::Parser::Result::Comment

Comment result token.

#TAP::Parser::Result::Plan

Plan result token.

#TAP::Parser::Result::Pragma

TAP pragma token.

#TAP::Parser::Result::Test

Test result token.

#TAP::Parser::Result::Unknown

Unknown result token.

#TAP::Parser::Result::Version

TAP syntax version token.

#TAP::Parser::Result::YAML

YAML result token.

#TAP::Parser::ResultFactory

Factory for creating TAP::Parser output objects

#TAP::Parser::Scheduler

Schedule tests during parallel testing

#TAP::Parser::Scheduler::Job

A single testing job.

#TAP::Parser::Scheduler::Spinner

A no-op job.

#TAP::Parser::Source

A TAP source & meta data about it

#TAP::Parser::SourceHandler

Base class for different TAP source handlers

#TAP::Parser::SourceHandler::Executable

Stream output from an executable TAP source

#TAP::Parser::SourceHandler::File

Stream TAP from a text file.

#TAP::Parser::SourceHandler::Handle

Stream TAP from an IO::Handle or a GLOB.

#TAP::Parser::SourceHandler::Perl

Stream TAP from a Perl executable

#TAP::Parser::SourceHandler::RawTAP

Stream output from raw TAP in a scalar/array ref.

#TAP::Parser::YAMLish::Reader

Read YAMLish data from iterator

#TAP::Parser::YAMLish::Writer

Write YAMLish data

#Term::ANSIColor

Color screen output using ANSI escape sequences

#Term::Cap

Perl termcap interface

#Term::Complete

Perl word completion module

#Term::ReadLine

Perl interface to variousreadline packages.

#Term::Table

Format a header and rows into a table

#Term::Table::Cell

Representation of a cell in a table.

#Term::Table::CellStack

Combine several cells into one (vertical)

#Term::Table::HashBase

Build hash based classes.

#Term::Table::LineBreak

Break up lines for use in tables.

#Term::Table::Util

Utilities for Term::Table.

#Test

Provides a simple framework for writing test scripts

#Test2

Framework for writing test tools that all work together.

#Test2::API

Primary interface for writing Test2 based testing tools.

#Test2::API::Breakage

What breaks at what version

#Test2::API::Context

Object to represent a testing context.

#Test2::API::Instance

Object used by Test2::API under the hood

#Test2::API::InterceptResult

Representation of a list of events.

#Test2::API::InterceptResult::Event

Representation of an event for use in

#Test2::API::InterceptResult::Hub

Hub used by InterceptResult.

#Test2::API::InterceptResult::Squasher

Encapsulation of the algorithm that

#Test2::API::Stack

Object to manage a stack ofTest2::Hub

#Test2::AsyncSubtest

Object representing an async subtest.

#Test2::AsyncSubtest::Event::Attach

Event to attach a subtest to the parent.

#Test2::AsyncSubtest::Event::Detach

Event to detach a subtest from the parent.

#Test2::AsyncSubtest::Hub

Hub used by async subtests.

#Test2::Bundle

Documentation for bundles.

#Test2::Bundle::Extended

Old name for Test2::V0

#Test2::Bundle::More

ALMOST a drop-in replacement for Test::More.

#Test2::Bundle::Simple

ALMOST a drop-in replacement for Test::Simple.

#Test2::Compare

Test2 extension for writing deep comparison tools.

#Test2::Compare::Array

Internal representation of an array comparison.

#Test2::Compare::Bag

Internal representation of a bag comparison.

#Test2::Compare::Base

Base class for comparison classes.

#Test2::Compare::Bool

Compare two values as booleans

#Test2::Compare::Custom

Custom field check for comparisons.

#Test2::Compare::DeepRef

Ref comparison

#Test2::Compare::Delta

Representation of differences between nested data

#Test2::Compare::Event

Event specific Object subclass.

#Test2::Compare::EventMeta

Meta class for events in deep comparisons

#Test2::Compare::Float

Compare two values as numbers with tolerance.

#Test2::Compare::Hash

Representation of a hash in a deep comparison.

#Test2::Compare::Isa

Check if the value is an instance of the class.

#Test2::Compare::Meta

Check library for meta-checks

#Test2::Compare::Negatable

Poor mans 'role' for compare objects that can be negated.

#Test2::Compare::Number

Compare two values as numbers

#Test2::Compare::Object

Representation of an object during deep

#Test2::Compare::OrderedSubset

Internal representation of an ordered subset.

#Test2::Compare::Pattern

Use a pattern to validate values in a deep

#Test2::Compare::Ref

Ref comparison

#Test2::Compare::Regex

Regex direct comparison

#Test2::Compare::Scalar

Representation of a Scalar Ref in deep

#Test2::Compare::Set

Allows a field to be matched against a set of

#Test2::Compare::String

Compare two values as strings

#Test2::Compare::Undef

Check that something is undefined

#Test2::Compare::Wildcard

Placeholder check.

#Test2::Event

Base class for events

#Test2::Event::Bail

Bailout!

#Test2::Event::Diag

Diag event type

#Test2::Event::Encoding

Set the encoding for the output stream

#Test2::Event::Exception

Exception event

#Test2::Event::Fail

Event for a simple failed assertion

#Test2::Event::Generic

Generic event type.

#Test2::Event::Note

Note event type

#Test2::Event::Ok

Ok event type

#Test2::Event::Pass

Event for a simple passing assertion

#Test2::Event::Plan

The event of a plan

#Test2::Event::Skip

Skip event type

#Test2::Event::Subtest

Event for subtest types

#Test2::Event::TAP::Version

Event for TAP version.

#Test2::Event::V2

Second generation event.

#Test2::Event::Waiting

Tell all procs/threads it is time to be done

#Test2::EventFacet

Base class for all event facets.

#Test2::EventFacet::About

Facet with event details.

#Test2::EventFacet::Amnesty

Facet for assertion amnesty.

#Test2::EventFacet::Assert

Facet representing an assertion.

#Test2::EventFacet::Control

Facet for hub actions and behaviors.

#Test2::EventFacet::Error

Facet for errors that need to be shown.

#Test2::EventFacet::Hub

Facet for the hubs an event passes through.

#Test2::EventFacet::Info

Facet for information a developer might care about.

#Test2::EventFacet::Info::Table

Intermediary representation of a table.

#Test2::EventFacet::Meta

Facet for meta-data

#Test2::EventFacet::Parent

Facet for events contains other events

#Test2::EventFacet::Plan

Facet for setting the plan

#Test2::EventFacet::Render

Facet that dictates how to render an event.

#Test2::EventFacet::Trace

Debug information for events

#Test2::Formatter

Namespace for formatters.

#Test2::Formatter::TAP

Standard TAP formatter

#Test2::Hub

The conduit through which all events flow.

#Test2::Hub::Interceptor

Hub used by interceptor to grab results.

#Test2::Hub::Interceptor::Terminator

Exception class used by

#Test2::Hub::Subtest

Hub used by subtests

#Test2::IPC

Turn on IPC for threading or forking support.

#Test2::IPC::Driver

Base class for Test2 IPC drivers.

#Test2::IPC::Driver::Files

Temp dir + Files concurrency model.

#Test2::Manual

Documentation hub for Test2 and Test2-Suite.

#Test2::Manual::Anatomy

The hub for documentation of the inner workings of

#Test2::Manual::Anatomy::API

Internals documentation for the API.

#Test2::Manual::Anatomy::Context

Internals documentation for the Context

#Test2::Manual::Anatomy::EndToEnd

Overview of Test2 from load to finish.

#Test2::Manual::Anatomy::Event

The internals of events

#Test2::Manual::Anatomy::Hubs

Internals documentation for the hub stack, and

#Test2::Manual::Anatomy::IPC

Manual for the IPC system.

#Test2::Manual::Anatomy::Utilities

Overview of utilities for Test2.

#Test2::Manual::Concurrency

Documentation for Concurrency support.

#Test2::Manual::Contributing

How to contribute to the Test2 project.

#Test2::Manual::Testing

Hub for documentation about writing tests with Test2.

#Test2::Manual::Testing::Introduction

Introduction to testing with Test2.

#Test2::Manual::Testing::Migrating

How to migrate existing tests from

#Test2::Manual::Testing::Planning

The many ways to set a plan.

#Test2::Manual::Testing::Todo

Tutorial for marking tests as TODO.

#Test2::Manual::Tooling

Manual page for tool authors.

#Test2::Manual::Tooling::FirstTool

Write your first tool with Test2.

#Test2::Manual::Tooling::Formatter

How to write a custom formatter, in our

#Test2::Manual::Tooling::Nesting

Tutorial for using other tools within your

#Test2::Manual::Tooling::Plugin::TestExit

How to safely add pre-exit

#Test2::Manual::Tooling::Plugin::TestingDone

Run code when the test file is

#Test2::Manual::Tooling::Plugin::ToolCompletes

How to add behaviors that occur

#Test2::Manual::Tooling::Plugin::ToolStarts

How to add behaviors that occur

#Test2::Manual::Tooling::Subtest

How to implement a tool that makes use of

#Test2::Manual::Tooling::TestBuilder

This section maps Test::Builder methods

#Test2::Manual::Tooling::Testing

Tutorial on how to test your testing tools.

#Test2::Mock

Module for managing mocked classes and instances.

#Test2::Plugin

Documentation for plugins

#Test2::Plugin::BailOnFail

Automatically bail out of testing on the first test

#Test2::Plugin::DieOnFail

Automatically die on the first test failure.

#Test2::Plugin::ExitSummary

Add extra diagnostics on failure at the end of the

#Test2::Plugin::SRand

Control the random seed for more controlled test

#Test2::Plugin::Times

Output timing data at the end of the test.

#Test2::Plugin::UTF8

Test2 plugin to test with utf8.

#Test2::Require

Base class and documentation for skip-unless type test

#Test2::Require::AuthorTesting

Only run a test when the AUTHOR_TESTING

#Test2::Require::AutomatedTesting

Only run a test when the AUTOMATED_TESTING

#Test2::Require::EnvVar

Only run a test when a specific environment variable

#Test2::Require::ExtendedTesting

Only run a test when the EXTENDED_TESTING

#Test2::Require::Fork

Skip a test file unless the system supports forking

#Test2::Require::Module

Skip tests if certain packages are not installed, or

#Test2::Require::NonInteractiveTesting

Only run a test when the NONINTERACTIVE_TESTING

#Test2::Require::Perl

Skip the test unless the necessary version of Perl is

#Test2::Require::RealFork

Skip a test file unless the system supports true

#Test2::Require::ReleaseTesting

Only run a test when the RELEASE_TESTING

#Test2::Require::Threads

Skip a test file unless the system supports threading

#Test2::Suite

Distribution with a rich set of tools built upon the Test2

#Test2::Todo

TODO extension for Test2.

#Test2::Tools

Documentation for Tools.

#Test2::Tools::AsyncSubtest

Tools for writing async subtests.

#Test2::Tools::Basic

Test2 implementation of the basic testing tools.

#Test2::Tools::Class

Test2 implementation of the tools for testing classes.

#Test2::Tools::ClassicCompare

Classic (Test::More style) comparison tools.

#Test2::Tools::Compare

Tools for comparing deep data structures.

#Test2::Tools::Defer

Write tests that get executed at a later time

#Test2::Tools::Encoding

Tools for managing the encoding ofTest2 based

#Test2::Tools::Event

Tools for generating test events.

#Test2::Tools::Exception

Test2 based tools for checking exceptions

#Test2::Tools::Exports

Tools for validating exporters.

#Test2::Tools::GenTemp

Tool for generating a populated temp directory.

#Test2::Tools::Grab

Temporarily intercept all events without adding a scope

#Test2::Tools::Mock

Class/Instance mocking for Test2.

#Test2::Tools::Ref

Tools for validating references.

#Test2::Tools::Spec

RSPEC implementation on top of Test2::Workflow

#Test2::Tools::Subtest

Tools for writing subtests

#Test2::Tools::Target

Alias the testing target package.

#Test2::Tools::Tester

Tools to help you test other testing tools.

#Test2::Tools::Tiny

Tiny set of tools for unfortunate souls who cannot use

#Test2::Tools::Warnings

Tools to verify warnings.

#Test2::Transition

Transition notes when upgrading to Test2

#Test2::Util

Tools used by Test2 and friends.

#Test2::Util::ExternalMeta

Allow third party tools to safely attach meta-data

#Test2::Util::Facets2Legacy

Convert facet data to the legacy event API.

#Test2::Util::Grabber

Object used to temporarily intercept all events.

#Test2::Util::Guard

Inline copy ofScope::Guard

#Test2::Util::HashBase

Build hash based classes.

#Test2::Util::Importer

Inline copy ofImporter.

#Test2::Util::Ref

Tools for inspecting or manipulating references.

#Test2::Util::Stash

Utilities for manipulating stashes and globs.

#Test2::Util::Sub

Tools for inspecting and manipulating subs.

#Test2::Util::Table

Format a header and rows into a table

#Test2::Util::Table::LineBreak

Break up lines for use in tables.

#Test2::Util::Times

Format timing/benchmark information.

#Test2::Util::Trace

Legacy wrapper froTest2::EventFacet::Trace.

#Test2::V0

0Th edition of the Test2 recommended bundle.

#Test2::Workflow

A test workflow is a way of structuring tests using

#Test2::Workflow::BlockBase

Base class for all workflow blocks.

#Test2::Workflow::Build

Represents a build in progress.

#Test2::Workflow::Runner

Runs the workflows.

#Test2::Workflow::Task

Encapsulation of a Task

#Test2::Workflow::Task::Action

Encapsulation of an action.

#Test2::Workflow::Task::Group

Encapsulation of a group (describe).

#Test::Builder

Backend for building test libraries

#Test::Builder::Formatter

Test::Builder subclass of Test2::Formatter::TAP

#Test::Builder::IO::Scalar

A copy of IO::Scalar for Test::Builder

#Test::Builder::Module

Base class for test modules

#Test::Builder::Tester

Test testsuites that have been built with

#Test::Builder::Tester::Color

Turn on colour in Test::Builder::Tester

#Test::Builder::TodoDiag

Test::Builder subclass of Test2::Event::Diag

#Test::Harness

Run Perl standard test scripts with statistics

#Test::Harness::Beyond

Beyond make test

#Test::More

Yet another framework for writing test scripts

#Test::Simple

Basic utilities for writing tests.

#Test::Tester

Ease testing test modules built with Test::Builder

#Test::Tester::Capture

Help testing test modules built with Test::Builder

#Test::Tester::CaptureRunner

Help testing test modules built with Test::Builder

#Test::Tutorial

A tutorial about writing really basic tests

#Test::use::ok

Alternative to Test::More::use_ok

#Text::Abbrev

Abbrev - create an abbreviation table from a list

#Text::Balanced

Extract delimited text sequences from strings.

#Text::ParseWords

Parse text into an array of tokens or array of arrays

#Text::Tabs

Expand and unexpand tabs like unix expand(1) and unexpand(1)

#Text::Wrap

Line wrapping to form simple paragraphs

#Thread

Manipulate threads in Perl (for old code only)

#Thread::Queue

Thread-safe queues

#Thread::Semaphore

Thread-safe semaphores

#Tie::Array

Base class for tied arrays

#Tie::File

Access the lines of a disk file via a Perl array

#Tie::Handle

Base class definitions for tied handles

#Tie::Hash

Base class definitions for tied hashes

#Tie::Hash::NamedCapture

Named regexp capture buffers

#Tie::Memoize

Add data to hash when needed

#Tie::RefHash

Use references as hash keys

#Tie::Scalar

Base class definitions for tied scalars

#Tie::StdHandle

Base class definitions for tied handles

#Tie::SubstrHash

Fixed-table-size, fixed-key-length hashing

#Time::HiRes

High resolution alarm, sleep, gettimeofday, interval timers

#Time::Local

Efficiently compute time from local and GMT time

#Time::Piece

Object Oriented time objects

#Time::Seconds

A simple API to convert seconds to other date values

#Time::gmtime

By-name interface to Perl's built-in gmtime() function

#Time::localtime

By-name interface to Perl's built-in localtime() function

#Time::tm

Internal object used by Time::gmtime and Time::localtime

#UNIVERSAL

Base class for ALL classes (blessed references)

#Unicode::Collate

Unicode Collation Algorithm

#Unicode::Collate::CJK::Big5

Weighting CJK Unified Ideographs

#Unicode::Collate::CJK::GB2312

Weighting CJK Unified Ideographs

#Unicode::Collate::CJK::JISX0208

Weighting JIS KANJI for Unicode::Collate

#Unicode::Collate::CJK::Korean

Weighting CJK Unified Ideographs

#Unicode::Collate::CJK::Pinyin

Weighting CJK Unified Ideographs

#Unicode::Collate::CJK::Stroke

Weighting CJK Unified Ideographs

#Unicode::Collate::CJK::Zhuyin

Weighting CJK Unified Ideographs

#Unicode::Collate::Locale

Linguistic tailoring for DUCET via Unicode::Collate

#Unicode::Normalize

Unicode Normalization Forms

#Unicode::UCD

Unicode character database

#User::grent

By-name interface to Perl's built-in getgr*() functions

#User::pwent

By-name interface to Perl's built-in getpw*() functions

#VMS::DCLsym

Perl extension to manipulate DCL symbols

#VMS::Filespec

Convert between VMS and Unix file specification syntax

#VMS::Stdio

Standard I/O functions via VMS extensions

#Win32

Interfaces to some Win32 API Functions

#Win32API::File

Low-level access to Win32 system API calls for files/dirs.

#Win32CORE

Win32 CORE function stubs

#XS::APItest

Test the perl C API

#XS::Typemap

Module to test the XS typemaps distributed with perl

#XSLoader

Dynamically load C libraries into Perl code

#autodie::Scope::Guard

Wrapper class for calling subs at end of scope

#autodie::Scope::GuardStack

Hook stack for managing scopes via %^H

#autodie::Util

Internal Utility subroutines for autodie and Fatal

#version::Internals

Perl extension for Version Objects

To find outall modules installed on your system, including those without documentation or outside the standard release, just use the following command (under the default win32 shell, double quotes should be used instead of single quotes).

% perl -MFile::Find=find -MFile::Spec::Functions -Tlwe \  'find { wanted => sub { print canonpath $_ if /\.pm\z/ },  no_chdir => 1 }, @INC'

(The -T is here to prevent @INC from being populated byPERL5LIB,PERLLIB, andPERL_USE_UNSAFE_INC.) They should all have their own documentation installed and accessible via your system man(1) command. If you do not have afind program, you can use the Perlfind2perl program instead, which generates Perl code as output you can run through perl. If you have aman program but it doesn't find your modules, you'll have to fix your manpath. Seeperl for details. If you have no systemman command, you might try theperldoc program.

Note also that the commandperldoc perllocal gives you a (possibly incomplete) list of the modules that have been further installed on your system. (The perllocal.pod file is updated by the standard MakeMaker install process.)

#Extension Modules

Extension modules are written in C (or a mix of Perl and C). They are usually dynamically loaded into Perl if and when you need them, but may also be linked in statically. Supported extension modules include Socket, Fcntl, and POSIX.

Many popular C extension modules do not come bundled (at least, not completely) due to their sizes, volatility, or simply lack of time for adequate testing and configuration across the multitude of platforms on which Perl was beta-tested. You are encouraged to look for them on CPAN (described below), or using web search engines like Google or DuckDuckGo.

#CPAN

CPAN stands for Comprehensive Perl Archive Network; it's a globally replicated trove of Perl materials, including documentation, style guides, tricks and traps, alternate ports to non-Unix systems and occasional binary distributions for these. Search engines for CPAN can be found at https://www.cpan.org/

Most importantly, CPAN includes around a thousand unbundled modules, some of which require a C compiler to build. Major categories of modules are:

• Language Extensions and Documentation Tools

• Development Support

• Operating System Interfaces

• Networking, Device Control (modems) and InterProcess Communication

• Data Types and Data Type Utilities

• Database Interfaces

• User Interfaces

• Interfaces to / Emulations of Other Programming Languages

• File Names, File Systems and File Locking (see also File Handles)

• String Processing, Language Text Processing, Parsing, and Searching

• Option, Argument, Parameter, and Configuration File Processing

• Internationalization and Locale

• Authentication, Security, and Encryption

• World Wide Web, HTML, HTTP, CGI, MIME

• Server and Daemon Utilities

• Archiving and Compression

• Images, Pixmap and Bitmap Manipulation, Drawing, and Graphing

• Mail and Usenet News

• Control Flow Utilities (callbacks and exceptions etc)

• File Handle and Input/Output Stream Utilities

• Miscellaneous Modules

You can find the CPAN online athttps://www.cpan.org/

#Modules: Creation, Use, and Abuse

(The following section is borrowed directly from Tim Bunce's modules file, available at your nearest CPAN site.)

Perl implements a class using a package, but the presence of a package doesn't imply the presence of a class. A package is just a namespace. A class is a package that provides subroutines that can be used as methods. A method is just a subroutine that expects, as its first argument, either the name of a package (for "static" methods), or a reference to something (for "virtual" methods).

A module is a file that (by convention) provides a class of the same name (sans the .pm), plus an import method in that class that can be called to fetch exported symbols. This module may implement some of its methods by loading dynamic C or C++ objects, but that should be totally transparent to the user of the module. Likewise, the module might set up an AUTOLOAD function to slurp in subroutine definitions on demand, but this is also transparent. Only the.pm file is required to exist. Seeperlsub,perlobj, andAutoLoader for details about the AUTOLOAD mechanism.

#Guidelines for Module Creation

• Do similar modules already exist in some form?

  If so, please try to reuse the existing modules either in whole or by inheriting useful features into a new class. If this is not practical try to get together with the module authors to work on extending or enhancing the functionality of the existing modules. A perfect example is the plethora of packages in perl4 for dealing with command line options.

  If you are writing a module to expand an already existing set of modules, please coordinate with the author of the package. It helps if you follow the same naming scheme and module interaction scheme as the original author.

• Try to design the new module to be easy to extend and reuse.

  Try touse warnings; (oruse warnings qw(...);). Remember that you can addno warnings qw(...); to individual blocks of code that need less warnings.

  Use blessed references. Use the two argument form of bless to bless into the class name given as the first parameter of the constructor, e.g.,:

  sub new {    my $class = shift;    return bless {}, $class;}

  or even this if you'd like it to be used as either a static or a virtual method.

  sub new {    my $self  = shift;    my $class = ref($self) || $self;    return bless {}, $class;}

  Pass arrays as references so more parameters can be added later (it's also faster). Convert functions into methods where appropriate. Split large methods into smaller more flexible ones. Inherit methods from other modules if appropriate.

  Avoid class name tests like:die "Invalid" unless ref $ref eq 'FOO'. Generally you can delete theeq 'FOO' part with no harm at all. Let the objects look after themselves! Generally, avoid hard-wired class names as far as possible.

  Avoid$r->Class::func() where using@ISA=qw(... Class ...) and$r->func() would work.

  Use autosplit so little used or newly added functions won't be a burden to programs that don't use them. Add test functions to the module after __END__ either using AutoSplit or by saying:

  eval join('',<main::DATA>) || die $@ unless caller();

  Does your module pass the 'empty subclass' test? If you say@SUBCLASS::ISA = qw(YOURCLASS); your applications should be able to use SUBCLASS in exactly the same way as YOURCLASS. For example, does your application still work if you change:$obj = YOURCLASS->new(); into:$obj = SUBCLASS->new(); ?

  Avoid keeping any state information in your packages. It makes it difficult for multiple other packages to use yours. Keep state information in objects.

  Always use-w.

  Try touse strict; (oruse strict qw(...);). Remember that you can addno strict qw(...); to individual blocks of code that need less strictness.

  Always use-w.

  Follow the guidelines inperlstyle.

  Always use-w.

• Some simple style guidelines

  The perlstyle manual supplied with Perl has many helpful points.

  Coding style is a matter of personal taste. Many people evolve their style over several years as they learn what helps them write and maintain good code. Here's one set of assorted suggestions that seem to be widely used by experienced developers:

  Use underscores to separate words. It is generally easier to read $var_names_like_this than $VarNamesLikeThis, especially for non-native speakers of English. It's also a simple rule that works consistently with VAR_NAMES_LIKE_THIS.

  Package/Module names are an exception to this rule. Perl informally reserves lowercase module names for 'pragma' modules like integer and strict. Other modules normally begin with a capital letter and use mixed case with no underscores (need to be short and portable).

  You may find it helpful to use letter case to indicate the scope or nature of a variable. For example:

  $ALL_CAPS_HERE   constants only (beware clashes with Perl vars)$Some_Caps_Here  package-wide global/static$no_caps_here    function scope my() or local() variables

  Function and method names seem to work best as all lowercase. e.g.,$obj->as_string().

  You can use a leading underscore to indicate that a variable or function should not be used outside the package that defined it.

• Select what to export.

  Do NOT export method names!

  Do NOT export anything else by default without a good reason!

  Exports pollute the namespace of the module user. If you must export try to use @EXPORT_OK in preference to @EXPORT and avoid short or common names to reduce the risk of name clashes.

  Generally anything not exported is still accessible from outside the module using the ModuleName::item_name (or$blessed_ref->method) syntax. By convention you can use a leading underscore on names to indicate informally that they are 'internal' and not for public use.

  (It is actually possible to get private functions by saying:my $subref = sub { ... }; &$subref;. But there's no way to call that directly as a method, because a method must have a name in the symbol table.)

  As a general rule, if the module is trying to be object oriented then export nothing. If it's just a collection of functions then @EXPORT_OK anything but use @EXPORT with caution.

• Select a name for the module.

  This name should be as descriptive, accurate, and complete as possible. Avoid any risk of ambiguity. Always try to use two or more whole words. Generally the name should reflect what is special about what the module does rather than how it does it. Please use nested module names to group informally or categorize a module. There should be a very good reason for a module not to have a nested name. Module names should begin with a capital letter.

  Having 57 modules all called Sort will not make life easy for anyone (though having 23 called Sort::Quick is only marginally better :-). Imagine someone trying to install your module alongside many others.

  If you are developing a suite of related modules/classes it's good practice to use nested classes with a common prefix as this will avoid namespace clashes. For example: Xyz::Control, Xyz::View, Xyz::Model etc. Use the modules in this list as a naming guide.

  If adding a new module to a set, follow the original author's standards for naming modules and the interface to methods in those modules.

  If developing modules for private internal or project specific use, that will never be released to the public, then you should ensure that their names will not clash with any future public module. You can do this either by using the reserved Local::* category or by using a category name that includes an underscore like Foo_Corp::*.

  To be portable each component of a module name should be limited to 11 characters. If it might be used on MS-DOS then try to ensure each is unique in the first 8 characters. Nested modules make this easier.

  For additional guidance on the naming of modules, please consult:

  https://pause.perl.org/pause/query?ACTION=pause_namingmodules

  or send mail to the <module-authors@perl.org> mailing list.

• Have you got it right?

  How do you know that you've made the right decisions? Have you picked an interface design that will cause problems later? Have you picked the most appropriate name? Do you have any questions?

  The best way to know for sure, and pick up many helpful suggestions, is to ask someone who knows. The <module-authors@perl.org> mailing list is useful for this purpose; it's also accessible via news interface as perl.module-authors at nntp.perl.org.

  All you need to do is post a short summary of the module, its purpose and interfaces. A few lines on each of the main methods is probably enough. (If you post the whole module it might be ignored by busy people - generally the very people you want to read it!)

  Don't worry about posting if you can't say when the module will be ready - just say so in the message. It might be worth inviting others to help you, they may be able to complete it for you!

• README and other Additional Files.

  It's well known that software developers usually fully document the software they write. If, however, the world is in urgent need of your software and there is not enough time to write the full documentation please at least provide a README file containing:

  • A description of the module/package/extension etc.

  • A copyright notice - see below.

  • Prerequisites - what else you may need to have.

  • How to build it - possible changes to Makefile.PL etc.

  • How to install it.

  • Recent changes in this release, especially incompatibilities

  • Changes / enhancements you plan to make in the future.

  If the README file seems to be getting too large you may wish to split out some of the sections into separate files: INSTALL, Copying, ToDo etc.

  • Adding a Copyright Notice.

    How you choose to license your work is a personal decision. The general mechanism is to assert your Copyright and then make a declaration of how others may copy/use/modify your work.

    Perl, for example, is supplied with two types of licence: The GNU GPL and The Artistic Licence (see the files README, Copying, and Artistic, orperlgpl andperlartistic). Larry has good reasons for NOT just using the GNU GPL.

    My personal recommendation, out of respect for Larry, Perl, and the Perl community at large is to state something simply like:

    Copyright (c) 1995 Your Name. All rights reserved.This program is free software; you can redistribute it and/ormodify it under the same terms as Perl itself.

    This statement should at least appear in the README file. You may also wish to include it in a Copying file and your source files. Remember to include the other words in addition to the Copyright.

  • Give the module a version/issue/release number.

    To be fully compatible with the Exporter and MakeMaker modules you should store your module's version number in a non-my package variable called $VERSION. This should be a positive floating point number with at least two digits after the decimal (i.e., hundredths, e.g.,$VERSION = "0.01"). Don't use a "1.3.2" style version. SeeExporter for details.

    It may be handy to add a function or method to retrieve the number. Use the number in announcements and archive file names when releasing the module (ModuleName-1.02.tar.Z). See perldoc ExtUtils::MakeMaker.pm for details.

  • How to release and distribute a module.

    If possible, register the module with CPAN. Follow the instructions and links on:

    https://www.cpan.org/modules/04pause.html

    and upload to:

    https://pause.perl.org/

    and notify <modules@perl.org>. This will allow anyone to install your module using thecpan tool distributed with Perl.

    By using the WWW interface you can ask the Upload Server to mirror your modules from your ftp or WWW site into your own directory on CPAN!

  • Take care when changing a released module.

    Always strive to remain compatible with previous released versions. Otherwise try to add a mechanism to revert to the old behavior if people rely on it. Document incompatible changes.

#Guidelines for Converting Perl 4 Library Scripts into Modules

• There is no requirement to convert anything.

  If it ain't broke, don't fix it! Perl 4 library scripts should continue to work with no problems. You may need to make some minor changes (like escaping non-array @'s in double quoted strings) but there is no need to convert a .pl file into a Module for just that.

• Consider the implications.

  All Perl applications that make use of the script will need to be changed (slightly) if the script is converted into a module. Is it worth it unless you plan to make other changes at the same time?

• Make the most of the opportunity.

  If you are going to convert the script to a module you can use the opportunity to redesign the interface. The guidelines for module creation above include many of the issues you should consider.

• The pl2pm utility will get you started.

  This utility will read *.pl files (given as parameters) and write corresponding *.pm files. The pl2pm utilities does the following:

  • Adds the standard Module prologue lines

  • Converts package specifiers from ' to ::

  • Converts die(...) to croak(...)

  • Several other minor changes

  Being a mechanical process pl2pm is not bullet proof. The converted code will need careful checking, especially any package statements. Don't delete the original .pl file till the new .pm one works!

#Guidelines for Reusing Application Code

• Complete applications rarely belong in the Perl Module Library.

• Many applications contain some Perl code that could be reused.

  Help save the world! Share your code in a form that makes it easy to reuse.

• Break-out the reusable code into one or more separate module files.

• Take the opportunity to reconsider and redesign the interfaces.

• In some cases the 'application' can then be reduced to a small

  fragment of code built on top of the reusable modules. In these cases the application could invoked as:

  % perl -e 'use Module::Name; method(@ARGV)' ...or% perl -mModule::Name ...    (in perl5.002 or higher)

#NOTE

Perl does not enforce private and public parts of its modules as you may have been used to in other languages like C++, Ada, or Modula-17. Perl doesn't have an infatuation with enforced privacy. It would prefer that you stayed out of its living room because you weren't invited, not because it has a shotgun.

The module and its user have a contract, part of which is common law, and part of which is "written". Part of the common law contract is that a module doesn't pollute any namespace it wasn't asked to. The written contract for the module (A.K.A. documentation) may make other provisions. But then you know when youuse RedefineTheWorld that you're redefining the world and willing to take the consequences.

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