PERLMODLIB(1) Perl Programmers Reference Guide PERLMODLIB(1)NAMEperlmodlib - 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 par-
ticular 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 docu-
mentation).
attributes Get/set subroutine or variable attributes
attrs Set/get attributes of a subroutine (deprecated)
autouse Postpone load of modules until a function is
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used
base Establish IS-A relationship with base classes 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 opera-
tions
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
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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 docu-
mentation 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 gen-
erate bytecode
B::Assembler
Assemble Perl bytecode
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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 pro-
grams
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
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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
CPAN::Version
Utility functions to compare CPAN versions
Carp Warn of errors (from perspective of caller)
Carp::Heavy Heavy machinery, 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
DBM_Filter Filter DBM keys/values
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
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Digest Modules that calculate message digests
Digest::MD5 Perl interface to the MD5 Algorithm
Digest::base
Digest base class
Digest::file
Calculate digests of files
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*
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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 punc-
tuation 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::Constant::Base
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Base class for ExtUtils::Constant objects
ExtUtils::Constant::Utils
Helper functions for ExtUtils::Constant
ExtUtils::Constant::XS
Base class for ExtUtils::Constant objects
ExtUtils::Embed
Utilities for embedding Perl in C/C++ applica-
tions
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_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
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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::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
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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
Parse file paths into directory, filename and
suffix.
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
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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::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
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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 identifica-
tion (ISO 4217)
Locale::Language
ISO two letter codes for language identification
(ISO 639)
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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/float math package
Math::BigInt::Calc
Pure Perl module to support Math::BigInt
Math::BigInt::CalcEmu
Emulate low-level math with BigInt code
Math::BigRat
Arbitrary big rational numbers
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 Stor-
able 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
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Memoize::NDBM_File
Glue to provide EXISTS for NDBM_File for Stor-
able use
Memoize::SDBM_File
Glue to provide EXISTS for SDBM_File for Stor-
able 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
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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, com-
mands, etc.
Pod::LaTeX Convert Pod data to formatted Latex
Pod::Man Convert POD data to formatted *roff input
Pod::ParseLink
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 transla-
tors
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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 documen-
tation
SDBM_File Tied access to sdbm files
Safe Compile and execute code in restricted compart-
ments
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Scalar::Util
A selection of general-utility scalar subrou-
tines
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 mani-
pulators
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::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
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Test::Harness
Run Perl standard test scripts with statistics
Test::Harness::Assert
Simple assert
Test::Harness::Iterator
Internal Test::Harness Iterator
Test::Harness::Point
Object for tracking a single test point
Test::Harness::Straps
Detailed analysis of test results
Test::Harness::TAP
Documentation for the TAP format
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
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Thread::Signal
Start a thread which runs signal handlers reli-
ably (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
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User::grent By-name interface to Perl's built-in getgr*()
functions
User::pwent By-name interface to Perl's built-in getpw*()
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. Sup-
ported 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.
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CPAN stands for Comprehensive Perl Archive Network; it's a
globally replicated trove of Perl materials, including docu-
mentation, 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 Pro-
cessing
+ 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
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+ 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
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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
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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/
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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/
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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
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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/
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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/
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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
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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/
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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
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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
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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
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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 enhanc-
ing 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 exist-
ing 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.
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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 indi-
vidual blocks of code that need less strictness.
Always use -w.
Follow the guidelines in the perlstyle(1) manual.
Always use -w.
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+ 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 $VarNamesLik-
eThis, 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
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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 com-
plete 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 exam-
ple: 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
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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 - gen-
erally 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.
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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 Mak-
eMaker modules you should store your module's ver-
sion 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 avai-
lability of your module (or the module itself if
small) to the comp.lang.perl.announce Usenet news-
group. This will at least ensure very wide once-off
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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 automati-
cally. 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
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to make some minor changes (like escaping non-array @'s
in double quoted strings) but there is no need to con-
vert 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, espe-
cially 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
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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 conse-
quences.
perl v5.8.8 2006-06-30 42
