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CONTENTS

#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

#attrs

Set/get attributes of a subroutine (deprecated)

#autouse

Postpone load of modules until a function is used

#base

Establish IS-A relationship with base class at compile time

#bigint

Transparent BigInteger support for Perl

#bignum

Transparent BigNumber support for Perl

#bigrat

Transparent BigNumber/BigRational support for Perl

#blib

Use MakeMaker's uninstalled version of a package

#bytes

Force byte semantics rather than character semantics

#charnames

Define character names for \N{named} string literal escapes

#constant

Declare constants

#diagnostics

Produce verbose warning diagnostics

#encoding

Allows you to write your script in non-ascii or non-utf8

#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 from the compiler

#lib

Manipulate @INC at compile time

#locale

Use and avoid POSIX locales for built-in operations

#open

Set default PerlIO layers for input and output

#ops

Restrict unsafe operations when compiling

#overload

Package for overloading perl operations

#re

Alter regular expression behaviour

#sigtrap

Enable simple signal handling

#sort

Control sort() behaviour

#strict

Restrict unsafe constructs

#subs

Predeclare sub names

#threads

Perl extension allowing use of interpreter based threads from perl

#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 (obsolete)

#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.

#AnyDBM_File

Provide framework for multiple DBMs

#Attribute::Handlers

Simpler definition of attribute handlers

#AutoLoader

Load subroutines only on demand

#AutoSplit

Split a package for autoloading

#B

The Perl Compiler

#B::Asmdata

Autogenerated data about Perl ops, used to generate bytecode

#B::Assembler

Assemble Perl bytecode

#B::Bblock

Walk basic blocks

#B::Bytecode

Perl compiler's bytecode backend

#B::C

Perl compiler's C backend

#B::CC

Perl compiler's optimized C translation backend

#B::Concise

Walk Perl syntax tree, printing concise info about ops

#B::Debug

Walk Perl syntax tree, printing debug info about ops

#B::Deparse

Perl compiler backend to produce perl code

#B::Disassembler

Disassemble Perl bytecode

#B::Lint

Perl lint

#B::Showlex

Show lexical variables used in functions or files

#B::Stackobj

Helper module for CC backend

#B::Stash

Show what stashes are loaded

#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

#ByteLoader

Load byte compiled perl code

#CGI

Simple Common Gateway Interface Class

#CGI::Apache

Backward compatibility module for CGI.pm

#CGI::Carp

CGI routines for writing to the HTTPD (or other) error log

#CGI::Cookie

Interface to Netscape Cookies

#CGI::Fast

CGI Interface for Fast CGI

#CGI::Pretty

Module to produce nicely formatted HTML code

#CGI::Push

Simple Interface to Server Push

#CGI::Switch

Backward compatibility module for defunct CGI::Switch

#CGI::Util

Internal utilities used by CGI module

#CPAN

Query, download and build perl modules from CPAN sites

#CPAN::FirstTime

Utility for CPAN::Config file Initialization

#CPAN::Nox

Wrapper around CPAN.pm without using any XS module

#Carp

Warn of errors (from perspective of caller)

#Carp::Heavy

No user serviceable parts inside

#Class::ISA

Report the search path for a class's ISA tree

#Class::Struct

Declare struct-like datatypes as Perl classes

#Config

Access Perl configuration information

#Cwd

Get pathname of current working directory

#DB

Programmatic interface to the Perl debugging API (draft, subject to

#DB_File

Perl5 access to Berkeley DB version 1.x

#Data::Dumper

Stringified perl data structures, suitable for both printing and eval

#Devel::DProf

A Perl code profiler

#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::base

Digest base class

#DirHandle

Supply object methods for directory handles

#Dumpvalue

Provides screen dump of Perl data.

#DynaLoader

Dynamically load C libraries into Perl code

#Encode

Character encodings

#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::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 'B' and 'Q' header encoding

#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::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::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_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_MacOS

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

#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_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_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::FAQ

Frequently Asked Questions About MakeMaker

#ExtUtils::MakeMaker::Tutorial

Writing a module with MakeMaker

#ExtUtils::MakeMaker::bytes

Version-agnostic bytes.pm

#ExtUtils::MakeMaker::vmsish

Platform-agnostic vmsish.pm

#ExtUtils::Manifest

Utilities to write and check a MANIFEST file

#ExtUtils::Mkbootstrap

Make a bootstrap file for use by DynaLoader

#ExtUtils::Mksymlists

Write linker options files for dynamic extension

#ExtUtils::Packlist

Manage .packlist files

#ExtUtils::testlib

Add blib/* directories to @INC

#Fatal

Replace functions with equivalents which succeed or die

#Fcntl

Load the C Fcntl.h defines

#File::Basename

Split a pathname into pieces

#File::CheckTree

Run many filetest checks on a tree

#File::Compare

Compare files or filehandles

#File::Copy

Copy files or filehandles

#File::DosGlob

DOS like globbing and then some

#File::Find

Traverse a directory tree.

#File::Glob

Perl extension for BSD glob routine

#File::Path

Create or remove directory trees

#File::Spec

Portably perform operations on file names

#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::Std

Process single-character switches with switch clustering

#Hash::Util

A selection of general-utility hash subroutines

#I18N::Collate

Compare 8-bit scalar data according to the current locale

#I18N::LangTags

Functions for dealing with RFC3066-style language tags

#I18N::LangTags::List

Tags and names for human languages

#I18N::Langinfo

Query locale information

#IO

Load various IO modules

#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 the select 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

#IPC::Open2

Open a process for both reading and writing

#IPC::Open3

Open a process for reading, writing, and error handling

#IPC::SysV

SysV IPC constants

#IPC::SysV::Msg

SysV Msg IPC object class

#IPC::SysV::Semaphore

SysV Semaphore IPC object class

#List::Util

A selection of general-utility list subroutines

#Locale::Constants

Constants for Locale codes

#Locale::Country

ISO codes for country identification (ISO 3166)

#Locale::Currency

ISO three letter codes for currency identification (ISO 4217)

#Locale::Language

ISO two letter codes for language identification (ISO 639)

#Locale::Maketext

Framework for localization

#Locale::Maketext::TPJ13

Article about software localization

#Locale::Script

ISO codes for script identification (ISO 15924)

#MIME::Base64

Encoding and decoding of base64 strings

#MIME::Base64::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::BigRat

Arbitrarily big rationals

#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::ExpireFile

Test for Memoize expiration semantics

#Memoize::ExpireTest

Test for Memoize expiration semantics

#Memoize::NDBM_File

Glue to provide EXISTS for NDBM_File for Storable use

#Memoize::SDBM_File

Glue to provide EXISTS for SDBM_File for Storable use

#Memoize::Storable

Store Memoized data in Storable database

#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::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

#PerlIO

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

#PerlIO::encoding

Encoding layer

#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::Find

Find POD documents in directory trees

#Pod::Functions

Group Perl's functions a la perlfunc.pod

#Pod::Html

Module to convert pod files to HTML

#Pod::InputObjects

Objects representing POD input paragraphs, commands, etc.

#Pod::LaTeX

Convert Pod data to formatted Latex

#Pod::Man

Convert POD data to formatted *roff input

Parse an L<> formatting code in POD text

#Pod::ParseUtils

Helpers for POD parsing and conversion

#Pod::Parser

Base class for creating POD filters and translators

#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::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::PlainText

Convert POD data to formatted ASCII text

#Pod::Plainer

Perl extension for converting Pod to old style Pod.

#Pod::Select

Extract selected sections of POD from input

#Pod::Text

Convert POD data to formatted ASCII 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

Print a usage message from embedded pod documentation

#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

Search for key in dictionary file

#SelectSaver

Save and restore selected file handle

#SelfLoader

Load functions only on demand

#Shell

Run shell commands transparently within perl

#Socket

Load the C socket.h defines and structure manipulators

#Storable

Persistence for Perl data structures

#Switch

A switch statement for Perl

#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

#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 various readline packages.

#Test

Provides a simple framework for writing test scripts

#Test::Builder

Backend for building test libraries

#Test::Harness

Run Perl standard test scripts with statistics

#Test::Harness::Assert

Simple assert

#Test::Harness::Iterator

Internal Test::Harness Iterator

#Test::Harness::Straps

Detailed analysis of test results

#Test::More

Yet another framework for writing test scripts

#Test::Simple

Basic utilities for writing tests.

#Test::Tutorial

A tutorial about writing really basic tests

#Text::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::Soundex

Implementation of the Soundex Algorithm as Described by Knuth

#Text::Tabs

Expand and unexpand tabs per the 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

#Thread::Signal

Start a thread which runs signal handlers reliably (for old code)

#Thread::Specific

Thread-specific keys

#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::Memoize

Add data to hash when needed

#Tie::RefHash

Use references as hash keys

#Tie::Scalar

Base class definitions for tied scalars

#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::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::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

#Win32

Interfaces to some Win32 API Functions

#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

To find out all 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 '.' from being listed in @INC.) They should all have their own documentation installed and accessible via your system man(1) command. If you do not have a find program, you can use the Perl find2perl program instead, which generates Perl code as output you can run through perl. If you have a man program but it doesn't find your modules, you'll have to fix your manpath. See perl for details. If you have no system man command, you might try the perldoc program.

Note also that the command perldoc 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 Alta Vista or Google.

#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 http://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

The list of the registered CPAN sites as of this writing follows. Please note that the sorting order is alphabetical on fields:

Continent | |-->Country | |-->[state/province] | |-->ftp | |-->[http]

and thus the North American servers happen to be listed between the European and the South American sites.

You should try to choose one close to you.

#Africa

#South Africa
http://ftp.rucus.ru.ac.za/pub/perl/CPAN/
ftp://ftp.rucus.ru.ac.za/pub/perl/CPAN/
ftp://ftp.is.co.za/programming/perl/CPAN/
ftp://ftp.saix.net/pub/CPAN/
ftp://ftp.sun.ac.za/CPAN/CPAN/

#Asia

#China
http://cpan.linuxforum.net/
http://cpan.shellhung.org/
ftp://ftp.shellhung.org/pub/CPAN
ftp://mirrors.hknet.com/CPAN
#Indonesia
http://mirrors.tf.itb.ac.id/cpan/
http://cpan.cbn.net.id/
ftp://ftp.cbn.net.id/mirror/CPAN
#Israel
ftp://ftp.iglu.org.il/pub/CPAN/
http://cpan.lerner.co.il/
http://bioinfo.weizmann.ac.il/pub/software/perl/CPAN/
ftp://bioinfo.weizmann.ac.il/pub/software/perl/CPAN/
#Japan
ftp://ftp.u-aizu.ac.jp/pub/CPAN
ftp://ftp.kddlabs.co.jp/CPAN/
ftp://ftp.ayamura.org/pub/CPAN/
ftp://ftp.jaist.ac.jp/pub/lang/perl/CPAN/
http://ftp.cpan.jp/
ftp://ftp.cpan.jp/CPAN/
ftp://ftp.dti.ad.jp/pub/lang/CPAN/
ftp://ftp.ring.gr.jp/pub/lang/perl/CPAN/
#Malaysia
http://cpan.MyBSD.org.my
http://mirror.leafbug.org/pub/CPAN
http://ossig.mncc.com.my/mirror/pub/CPAN
#Russian Federation
http://cpan.tomsk.ru
ftp://cpan.tomsk.ru/
#Saudi Arabia
ftp://ftp.isu.net.sa/pub/CPAN/
#Singapore
http://CPAN.en.com.sg/
ftp://cpan.en.com.sg/
http://mirror.averse.net/pub/CPAN
ftp://mirror.averse.net/pub/CPAN
http://cpan.oss.eznetsols.org
ftp://ftp.oss.eznetsols.org/cpan
#South Korea
http://CPAN.bora.net/
ftp://ftp.bora.net/pub/CPAN/
http://mirror.kr.FreeBSD.org/CPAN
ftp://ftp.kr.FreeBSD.org/pub/CPAN
#Taiwan
ftp://ftp.nctu.edu.tw/UNIX/perl/CPAN
http://cpan.cdpa.nsysu.edu.tw/
ftp://cpan.cdpa.nsysu.edu.tw/pub/CPAN
http://ftp.isu.edu.tw/pub/CPAN
ftp://ftp.isu.edu.tw/pub/CPAN
ftp://ftp1.sinica.edu.tw/pub1/perl/CPAN/
http://ftp.tku.edu.tw/pub/CPAN/
ftp://ftp.tku.edu.tw/pub/CPAN/
#Thailand
ftp://ftp.loxinfo.co.th/pub/cpan/
ftp://ftp.cs.riubon.ac.th/pub/mirrors/CPAN/

#Central America

#Costa Rica
http://ftp.ucr.ac.cr/Unix/CPAN/
ftp://ftp.ucr.ac.cr/pub/Unix/CPAN/

#Europe

#Austria
http://cpan.inode.at/
ftp://cpan.inode.at
ftp://ftp.tuwien.ac.at/pub/CPAN/
#Belgium
http://ftp.easynet.be/pub/CPAN/
ftp://ftp.easynet.be/pub/CPAN/
http://cpan.skynet.be
ftp://ftp.cpan.skynet.be/pub/CPAN
ftp://ftp.kulnet.kuleuven.ac.be/pub/mirror/CPAN/
#Bosnia and Herzegovina
http://cpan.blic.net/
#Bulgaria
http://cpan.online.bg
ftp://cpan.online.bg/cpan
http://cpan.zadnik.org
ftp://ftp.zadnik.org/mirrors/CPAN/
http://cpan.lirex.net/
ftp://ftp.lirex.net/pub/mirrors/CPAN
#Croatia
http://ftp.linux.hr/pub/CPAN/
ftp://ftp.linux.hr/pub/CPAN/
#Czech Republic
ftp://ftp.fi.muni.cz/pub/CPAN/
ftp://sunsite.mff.cuni.cz/MIRRORS/ftp.funet.fi/pub/languages/perl/CPAN/
#Denmark
http://mirrors.sunsite.dk/cpan/
ftp://sunsite.dk/mirrors/cpan/
http://cpan.cybercity.dk
http://www.cpan.dk/CPAN/
ftp://www.cpan.dk/ftp.cpan.org/CPAN/
#Estonia
ftp://ftp.ut.ee/pub/languages/perl/CPAN/
#Finland
ftp://ftp.funet.fi/pub/languages/perl/CPAN/
http://mirror.eunet.fi/CPAN
#France
http://www.enstimac.fr/Perl/CPAN
http://ftp.u-paris10.fr/perl/CPAN
ftp://ftp.u-paris10.fr/perl/CPAN
http://cpan.mirrors.easynet.fr/
ftp://cpan.mirrors.easynet.fr/pub/ftp.cpan.org/
ftp://ftp.club-internet.fr/pub/perl/CPAN/
http://fr.cpan.org/
ftp://ftp.lip6.fr/pub/perl/CPAN/
ftp://ftp.oleane.net/pub/mirrors/CPAN/
ftp://ftp.pasteur.fr/pub/computing/CPAN/
http://mir2.ovh.net/ftp.cpan.org
ftp://mir1.ovh.net/ftp.cpan.org
http://ftp.crihan.fr/mirrors/ftp.cpan.org/
ftp://ftp.crihan.fr/mirrors/ftp.cpan.org/
http://ftp.u-strasbg.fr/CPAN
ftp://ftp.u-strasbg.fr/CPAN
ftp://cpan.cict.fr/pub/CPAN/
ftp://ftp.uvsq.fr/pub/perl/CPAN/
#Germany
ftp://ftp.rub.de/pub/CPAN/
ftp://ftp.freenet.de/pub/ftp.cpan.org/pub/CPAN/
ftp://ftp.uni-erlangen.de/pub/source/CPAN/
ftp://ftp-stud.fht-esslingen.de/pub/Mirrors/CPAN
http://pandemonium.tiscali.de/pub/CPAN/
ftp://pandemonium.tiscali.de/pub/CPAN/
http://ftp.gwdg.de/pub/languages/perl/CPAN/
ftp://ftp.gwdg.de/pub/languages/perl/CPAN/
ftp://ftp.uni-hamburg.de/pub/soft/lang/perl/CPAN/
ftp://ftp.leo.org/pub/CPAN/
http://cpan.noris.de/
ftp://cpan.noris.de/pub/CPAN/
ftp://ftp.mpi-sb.mpg.de/pub/perl/CPAN/
ftp://ftp.gmd.de/mirrors/CPAN/
#Greece
ftp://ftp.acn.gr/pub/lang/perl
ftp://ftp.forthnet.gr/pub/languages/perl/CPAN
ftp://ftp.ntua.gr/pub/lang/perl/
#Hungary
http://ftp.kfki.hu/packages/perl/CPAN/
ftp://ftp.kfki.hu/pub/packages/perl/CPAN/
#Iceland
http://ftp.rhnet.is/pub/CPAN/
ftp://ftp.rhnet.is/pub/CPAN/
#Ireland
http://cpan.indigo.ie/
ftp://cpan.indigo.ie/pub/CPAN/
http://ftp.heanet.ie/mirrors/ftp.perl.org/pub/CPAN
ftp://ftp.heanet.ie/mirrors/ftp.perl.org/pub/CPAN
http://sunsite.compapp.dcu.ie/pub/perl/
ftp://sunsite.compapp.dcu.ie/pub/perl/
#Italy
http://cpan.nettuno.it/
http://gusp.dyndns.org/CPAN/
ftp://gusp.dyndns.org/pub/CPAN
http://softcity.iol.it/cpan
ftp://softcity.iol.it/pub/cpan
ftp://ftp.unina.it/pub/Other/CPAN/CPAN/
ftp://ftp.unipi.it/pub/mirror/perl/CPAN/
ftp://cis.uniRoma2.it/CPAN/
ftp://ftp.edisontel.it/pub/CPAN_Mirror/
http://cpan.flashnet.it/
ftp://ftp.flashnet.it/pub/CPAN/
#Latvia
http://kvin.lv/pub/CPAN/
#Lithuania
ftp://ftp.unix.lt/pub/CPAN/
#Netherlands
ftp://download.xs4all.nl/pub/mirror/CPAN/
ftp://ftp.nl.uu.net/pub/CPAN/
ftp://ftp.nluug.nl/pub/languages/perl/CPAN/
http://cpan.cybercomm.nl/
ftp://mirror.cybercomm.nl/pub/CPAN
ftp://mirror.vuurwerk.nl/pub/CPAN/
ftp://ftp.cpan.nl/pub/CPAN/
http://ftp.easynet.nl/mirror/CPAN
ftp://ftp.easynet.nl/mirror/CPAN
http://archive.cs.uu.nl/mirror/CPAN/
ftp://ftp.cs.uu.nl/mirror/CPAN/
#Norway
ftp://ftp.uninett.no/pub/languages/perl/CPAN
ftp://ftp.uit.no/pub/languages/perl/cpan/
#Poland
ftp://ftp.mega.net.pl/CPAN
ftp://ftp.man.torun.pl/pub/doc/CPAN/
ftp://sunsite.icm.edu.pl/pub/CPAN/
#Portugal
ftp://ftp.ua.pt/pub/CPAN/
ftp://perl.di.uminho.pt/pub/CPAN/
http://cpan.dei.uc.pt/
ftp://ftp.dei.uc.pt/pub/CPAN
ftp://ftp.nfsi.pt/pub/CPAN
http://ftp.linux.pt/pub/mirrors/CPAN
ftp://ftp.linux.pt/pub/mirrors/CPAN
http://cpan.ip.pt/
ftp://cpan.ip.pt/pub/cpan/
http://cpan.telepac.pt/
ftp://ftp.telepac.pt/pub/cpan/
#Romania
ftp://ftp.bio-net.ro/pub/CPAN
ftp://ftp.kappa.ro/pub/mirrors/ftp.perl.org/pub/CPAN/
ftp://ftp.lug.ro/CPAN
ftp://ftp.roedu.net/pub/CPAN/
ftp://ftp.dntis.ro/pub/cpan/
ftp://ftp.iasi.roedu.net/pub/mirrors/ftp.cpan.org/
http://cpan.ambra.ro/
ftp://ftp.ambra.ro/pub/CPAN
ftp://ftp.dnttm.ro/pub/CPAN/
ftp://ftp.lasting.ro/pub/CPAN
ftp://ftp.timisoara.roedu.net/mirrors/CPAN/
#Russia
ftp://ftp.chg.ru/pub/lang/perl/CPAN/
http://cpan.rinet.ru/
ftp://cpan.rinet.ru/pub/mirror/CPAN/
ftp://ftp.aha.ru/pub/CPAN/
ftp://ftp.corbina.ru/pub/CPAN/
http://cpan.sai.msu.ru/
ftp://ftp.sai.msu.su/pub/lang/perl/CPAN/
#Slovakia
ftp://ftp.cvt.stuba.sk/pub/CPAN/
#Slovenia
ftp://ftp.arnes.si/software/perl/CPAN/
#Spain
http://cpan.imasd.elmundo.es/
ftp://ftp.rediris.es/mirror/CPAN/
ftp://ftp.ri.telefonica-data.net/CPAN
ftp://ftp.etse.urv.es/pub/perl/
#Sweden
http://ftp.du.se/CPAN/
ftp://ftp.du.se/pub/CPAN/
http://mirror.dataphone.se/CPAN
ftp://mirror.dataphone.se/pub/CPAN
ftp://ftp.sunet.se/pub/lang/perl/CPAN/
#Switzerland
http://cpan.mirror.solnet.ch/
ftp://ftp.solnet.ch/mirror/CPAN/
ftp://ftp.danyk.ch/CPAN/
ftp://sunsite.cnlab-switch.ch/mirror/CPAN/
#Turkey
http://ftp.ulak.net.tr/perl/CPAN/
ftp://ftp.ulak.net.tr/perl/CPAN
ftp://sunsite.bilkent.edu.tr/pub/languages/CPAN/
#Ukraine
http://cpan.org.ua/
ftp://cpan.org.ua/
ftp://ftp.perl.org.ua/pub/CPAN/
http://no-more.kiev.ua/CPAN/
ftp://no-more.kiev.ua/pub/CPAN/
#United Kingdom
http://www.mirror.ac.uk/sites/ftp.funet.fi/pub/languages/perl/CPAN
ftp://ftp.mirror.ac.uk/sites/ftp.funet.fi/pub/languages/perl/CPAN/
http://cpan.teleglobe.net/
ftp://cpan.teleglobe.net/pub/CPAN
http://cpan.mirror.anlx.net/
ftp://ftp.mirror.anlx.net/CPAN/
http://cpan.etla.org/
ftp://cpan.etla.org/pub/CPAN
ftp://ftp.demon.co.uk/pub/CPAN/
http://cpan.m.flirble.org/
ftp://ftp.flirble.org/pub/languages/perl/CPAN/
ftp://ftp.plig.org/pub/CPAN/
http://cpan.hambule.co.uk/
http://cpan.mirrors.clockerz.net/
ftp://ftp.clockerz.net/pub/CPAN/
ftp://usit.shef.ac.uk/pub/packages/CPAN/

#North America

#Canada
#Alberta
http://cpan.sunsite.ualberta.ca/
ftp://cpan.sunsite.ualberta.ca/pub/CPAN/
#Manitoba
http://theoryx5.uwinnipeg.ca/pub/CPAN/
ftp://theoryx5.uwinnipeg.ca/pub/CPAN/
#Nova Scotia
ftp://cpan.chebucto.ns.ca/pub/CPAN/
#Ontario
ftp://ftp.nrc.ca/pub/CPAN/
#Mexico
http://cpan.azc.uam.mx
ftp://cpan.azc.uam.mx/mirrors/CPAN
http://www.cpan.unam.mx/
ftp://ftp.unam.mx/pub/CPAN
http://www.msg.com.mx/CPAN/
ftp://ftp.msg.com.mx/pub/CPAN/
#United States
#Alabama
http://mirror.hiwaay.net/CPAN/
ftp://mirror.hiwaay.net/CPAN/
#California
http://cpan.develooper.com/
http://www.cpan.org/
ftp://cpan.valueclick.com/pub/CPAN/
http://www.mednor.net/ftp/pub/mirrors/CPAN/
ftp://ftp.mednor.net/pub/mirrors/CPAN/
http://mirrors.gossamer-threads.com/CPAN
ftp://cpan.nas.nasa.gov/pub/perl/CPAN/
http://mirrors.kernel.org/cpan/
ftp://mirrors.kernel.org/pub/CPAN
http://cpan-sj.viaverio.com/
ftp://cpan-sj.viaverio.com/pub/CPAN/
http://cpan.digisle.net/
ftp://cpan.digisle.net/pub/CPAN
http://www.perl.com/CPAN/
http://www.uberlan.net/CPAN
#Colorado
ftp://ftp.cs.colorado.edu/pub/perl/CPAN/
http://cpan.four10.com
#Delaware
http://ftp.lug.udel.edu/pub/CPAN
ftp://ftp.lug.udel.edu/pub/CPAN
#District of Columbia
ftp://ftp.dc.aleron.net/pub/CPAN/
#Florida
ftp://ftp.cise.ufl.edu/pub/mirrors/CPAN/
http://mirror.csit.fsu.edu/pub/CPAN/
ftp://mirror.csit.fsu.edu/pub/CPAN/
http://cpan.mirrors.nks.net/
#Indiana
ftp://ftp.uwsg.iu.edu/pub/perl/CPAN/
http://cpan.netnitco.net/
ftp://cpan.netnitco.net/pub/mirrors/CPAN/
http://archive.progeny.com/CPAN/
ftp://archive.progeny.com/CPAN/
http://fx.saintjoe.edu/pub/CPAN
ftp://ftp.saintjoe.edu/pub/CPAN
http://csociety-ftp.ecn.purdue.edu/pub/CPAN
ftp://csociety-ftp.ecn.purdue.edu/pub/CPAN
#Kentucky
http://cpan.uky.edu/
ftp://cpan.uky.edu/pub/CPAN/
http://slugsite.louisville.edu/cpan
ftp://slugsite.louisville.edu/CPAN
#Massachusetts
http://mirrors.towardex.com/CPAN
ftp://mirrors.towardex.com/pub/CPAN
ftp://ftp.ccs.neu.edu/net/mirrors/ftp.funet.fi/pub/languages/perl/CPAN/
#Michigan
ftp://cpan.cse.msu.edu/
http://cpan.calvin.edu/pub/CPAN
ftp://cpan.calvin.edu/pub/CPAN
#Nevada
http://www.oss.redundant.com/pub/CPAN
ftp://www.oss.redundant.com/pub/CPAN
#New Jersey
http://ftp.cpanel.net/pub/CPAN/
ftp://ftp.cpanel.net/pub/CPAN/
http://cpan.teleglobe.net/
ftp://cpan.teleglobe.net/pub/CPAN
#New York
http://cpan.belfry.net/
http://cpan.erlbaum.net/
ftp://cpan.erlbaum.net/
http://cpan.thepirtgroup.com/
ftp://cpan.thepirtgroup.com/
ftp://ftp.stealth.net/pub/CPAN/
http://www.rge.com/pub/languages/perl/
ftp://ftp.rge.com/pub/languages/perl/
#North Carolina
http://www.ibiblio.org/pub/languages/perl/CPAN
ftp://ftp.ibiblio.org/pub/languages/perl/CPAN
ftp://ftp.duke.edu/pub/perl/
ftp://ftp.ncsu.edu/pub/mirror/CPAN/
#Oklahoma
ftp://ftp.ou.edu/mirrors/CPAN/
#Oregon
ftp://ftp.orst.edu/pub/CPAN
#Pennsylvania
http://ftp.epix.net/CPAN/
ftp://ftp.epix.net/pub/languages/perl/
http://mirrors.phenominet.com/pub/CPAN/
ftp://mirrors.phenominet.com/pub/CPAN/
http://cpan.pair.com/
ftp://cpan.pair.com/pub/CPAN/
ftp://carroll.cac.psu.edu/pub/CPAN/
#Tennessee
ftp://ftp.sunsite.utk.edu/pub/CPAN/
#Texas
http://ftp.sedl.org/pub/mirrors/CPAN/
http://www.binarycode.org/cpan
ftp://mirror.telentente.com/pub/CPAN
http://mirrors.theonlinerecordstore.com/CPAN
#Utah
ftp://mirror.xmission.com/CPAN/
#Virginia
http://cpan-du.viaverio.com/
ftp://cpan-du.viaverio.com/pub/CPAN/
http://mirrors.rcn.net/pub/lang/CPAN/
ftp://mirrors.rcn.net/pub/lang/CPAN/
http://perl.secsup.org/
ftp://perl.secsup.org/pub/perl/
http://noc.cvaix.com/mirrors/CPAN/
#Washington
http://cpan.llarian.net/
ftp://cpan.llarian.net/pub/CPAN/
http://cpan.mirrorcentral.com/
ftp://ftp.mirrorcentral.com/pub/CPAN/
ftp://ftp-mirror.internap.com/pub/CPAN/
#Wisconsin
http://mirror.sit.wisc.edu/pub/CPAN/
ftp://mirror.sit.wisc.edu/pub/CPAN/
http://mirror.aphix.com/CPAN
ftp://mirror.aphix.com/pub/CPAN

#Oceania

#Australia
http://ftp.planetmirror.com/pub/CPAN/
ftp://ftp.planetmirror.com/pub/CPAN/
ftp://mirror.aarnet.edu.au/pub/perl/CPAN/
ftp://cpan.topend.com.au/pub/CPAN/
http://cpan.mirrors.ilisys.com.au
#New Zealand
ftp://ftp.auckland.ac.nz/pub/perl/CPAN/
#United States
http://aniani.ifa.hawaii.edu/CPAN/
ftp://aniani.ifa.hawaii.edu/CPAN/

#South America

#Argentina
ftp://mirrors.bannerlandia.com.ar/mirrors/CPAN/
http://www.linux.org.ar/mirrors/cpan
ftp://ftp.linux.org.ar/mirrors/cpan
#Brazil
ftp://cpan.pop-mg.com.br/pub/CPAN/
ftp://ftp.matrix.com.br/pub/perl/CPAN/
http://cpan.hostsul.com.br/
ftp://cpan.hostsul.com.br/
#Chile
http://cpan.netglobalis.net/
ftp://cpan.netglobalis.net/pub/CPAN/

#RSYNC Mirrors

www.linux.org.ar::cpan
theoryx5.uwinnipeg.ca::CPAN
ftp.shellhung.org::CPAN
rsync.nic.funet.fi::CPAN
ftp.u-paris10.fr::CPAN
mir1.ovh.net::CPAN
rsync://ftp.crihan.fr::CPAN
ftp.gwdg.de::FTP/languages/perl/CPAN/
ftp.leo.org::CPAN
ftp.cbn.net.id::CPAN
rsync://ftp.heanet.ie/mirrors/ftp.perl.org/pub/CPAN
ftp.iglu.org.il::CPAN
gusp.dyndns.org::cpan
ftp.kddlabs.co.jp::cpan
ftp.ayamura.org::pub/CPAN/
mirror.leafbug.org::CPAN
rsync.en.com.sg::CPAN
mirror.averse.net::cpan
rsync.oss.eznetsols.org
ftp.kr.FreeBSD.org::CPAN
ftp.solnet.ch::CPAN
cpan.cdpa.nsysu.edu.tw::CPAN
cpan.teleglobe.net::CPAN
rsync://rsync.mirror.anlx.net::CPAN
ftp.sedl.org::cpan
ibiblio.org::CPAN
cpan-du.viaverio.com::CPAN
aniani.ifa.hawaii.edu::CPAN
archive.progeny.com::CPAN
rsync://slugsite.louisville.edu::CPAN
mirror.aphix.com::CPAN
cpan.teleglobe.net::CPAN
ftp.lug.udel.edu::cpan
mirrors.kernel.org::mirrors/CPAN
mirrors.phenominet.com::CPAN
cpan.pair.com::CPAN
cpan-sj.viaverio.com::CPAN
mirror.csit.fsu.edu::CPAN
csociety-ftp.ecn.purdue.edu::CPAN

For an up-to-date listing of CPAN sites, see http://www.cpan.org/SITES or ftp://www.cpan.org/SITES .

#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. See perlsub, perltoot, and AutoLoader 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 to use warnings; (or use warnings qw(...);). Remember that you can add no 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 the eq '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 (see perlbot for more details).

    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 = new YOURCLASS; into: $obj = new SUBCLASS; ?

    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 to use strict; (or use strict qw(...);). Remember that you can add no strict qw(...); to individual blocks of code that need less strictness.

    Always use -w.

    Follow the guidelines in the perlstyle(1) manual.

    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 in any doubt ask for suggestions in comp.lang.perl.misc.

    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.

  • 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. Comp.lang.perl.misc is read by just about all the people who develop modules and it's the best place to ask.

    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, or perlgpl and perlartistic). 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/or
modify 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 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. See Exporter 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.

      It's good idea to post an announcement of the availability of your module (or the module itself if small) to the comp.lang.perl.announce Usenet newsgroup. This will at least ensure very wide once-off distribution.

      If possible, register the module with CPAN. You should include details of its location in your announcement.

      Some notes about ftp archives: Please use a long descriptive file name that includes the version number. Most incoming directories will not be readable/listable, i.e., you won't be able to see your file after uploading it. Remember to send your email notification message as soon as possible after uploading else your file may get deleted automatically. Allow time for the file to be processed and/or check the file has been processed before announcing its location.

      FTP Archives for Perl Modules:

      Follow the instructions and links on:

      http://www.cpan.org/modules/00modlist.long.html
http://www.cpan.org/modules/04pause.html

      or upload to one of these sites:

      https://pause.kbx.de/pause/
http://pause.perl.org/pause/

      and notify <modules@perl.org>.

      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!

      Please remember to send me an updated entry for the Module list!

    • 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 you use RedefineTheWorld that you're redefining the world and willing to take the consequences.

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