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PERLMODLIB(1) Perl Programmers Reference Guide PERLMODLIB(1)
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 sup-
plied 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 sub-
routines within a particular file rather than just a block. Such dec-
larations 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 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 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 byte-
code
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
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 print-
ing 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
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*
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 vari-
ables
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
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++ applications
ExtUtils::Install
Install files from here to there
ExtUtils::Installed
Inventory management of installed modules
ExtUtils::Liblist
Determine libraries to use and how to use them
ExtUtils::MM
OS adjusted ExtUtils::MakeMaker subclass
ExtUtils::MM_AIX
AIX specific subclass of ExtUtils::MM_Unix
ExtUtils::MM_Any
Platform-agnostic MM methods
ExtUtils::MM_BeOS
Methods to override UN*X behaviour in ExtUtils::MakeMaker
ExtUtils::MM_Cygwin
Methods to override UN*X behaviour in ExtUtils::MakeMaker
ExtUtils::MM_DOS
DOS specific subclass of ExtUtils::MM_Unix
ExtUtils::MM_MacOS
Once produced Makefiles for MacOS Classic
ExtUtils::MM_NW5
Methods to override UN*X behaviour in ExtUtils::MakeMaker
ExtUtils::MM_OS2
Methods to override UN*X behaviour in ExtUtils::MakeMaker
ExtUtils::MM_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
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
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
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/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 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
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 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::Builder::Module
Base class for test modules
Test::Builder::Tester
Test testsuites that have been built with
Test::Builder::Tester::Color
Turn on colour in Test::Builder::Tester
Test::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 unex-
pand(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
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 with-
out documentation or outside the standard release, just use the follow-
ing 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 sys-
tem 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 Make-
Maker 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 occa-
sional 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 mod-
ules are:
o Language Extensions and Documentation Tools
o Development Support
o Operating System Interfaces
o Networking, Device Control (modems) and InterProcess Communication
o Data Types and Data Type Utilities
o Database Interfaces
o User Interfaces
o Interfaces to / Emulations of Other Programming Languages
o File Names, File Systems and File Locking (see also File Handles)
o String Processing, Language Text Processing, Parsing, and Searching
o Option, Argument, Parameter, and Configuration File Processing
o Internationalization and Locale
o Authentication, Security, and Encryption
o World Wide Web, HTML, HTTP, CGI, MIME
o Server and Daemon Utilities
o Archiving and Compression
o Images, Pixmap and Bitmap Manipulation, Drawing, and Graphing
o Mail and Usenet News
o Control Flow Utilities (callbacks and exceptions etc)
o File Handle and Input/Output Stream Utilities
o 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
o 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.
o 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 con-
structor, 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 appropri-
ate. 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('',) || die $@ unless caller();
Does your module pass the 'empty subclass' test? If you say "@SUB-
CLASS::ISA = qw(YOURCLASS);" your applications should be able to
use SUBCLASS in exactly the same way as YOURCLASS. For example,
does your application still work if you change: "$obj = new YOUR-
CLASS;" 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.
o 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 con-
sistently 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.
o 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 lead-
ing 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.
o Select a name for the module.
This name should be as descriptive, accurate, and complete as pos-
sible. 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 any-
one (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 stan-
dards for naming modules and the interface to methods in those mod-
ules.
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.
o 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 sugges-
tions, 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 pur-
pose 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 oth-
ers to help you, they may be able to complete it for you!
o 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 docu-
mentation please at least provide a README file containing:
o A description of the module/package/extension etc.
o A copyright notice - see below.
o Prerequisites - what else you may need to have.
o How to build it - possible changes to Makefile.PL etc.
o How to install it.
o Recent changes in this release, especially incompatibili-
ties
o 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, Copy-
ing, ToDo etc.
o 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, Copy-
ing, 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.
o 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 pack-
age variable called $VERSION. This should be a floating point
number with at least two digits after the decimal (i.e., hun-
dredths, e.g, "$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.
o 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 pro-
cessed 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 .
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!
o Take care when changing a released module.
Always strive to remain compatible with previous released ver-
sions. 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
o There is no requirement to convert anything.
If it ain't broke, don't fix it! Perl 4 library scripts should con-
tinue 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.
o 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?
o 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.
o 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:
o Adds the standard Module prologue lines
o Converts package specifiers from ' to ::
o Converts die(...) to croak(...)
o 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
o Complete applications rarely belong in the Perl Module Library.
o 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.
o Break-out the reusable code into one or more separate module files.
o Take the opportunity to reconsider and redesign the interfaces.
o 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 pre-
fer 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.
perl v5.8.8 2006-01-07 PERLMODLIB(1)
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