--- name: "perlmodlib" section: "1" platform: "linux" package: "perl-doc" version: "5.40.1-6+deb13u1" release: "Debian 13 (Trixie)" platforms: ["linux", "openbsd"] url: "https://new.carta.tech/perlmodlib" --- # perlmodlib(1) constructing new Perl modules and finding existing ones ## NAME perlmodlib - constructing new Perl modules and finding existing ones ## THE PERL MODULE LIBRARY Many modules are included in the Perl distribution. These are described below, and all end in *.pm*. You may discover compiled library files (usually ending in *.so*) or small pieces of modules to be autoloaded (ending in *.al*); these were automatically generated by the installation process. You may also discover files in the library directory that end in either *.pl* or *.ph*. These are old libraries supplied so that old programs that use them still run. The *.pl* files will all eventually be converted into standard modules, and the *.ph* files made by **h2ph** will probably end up as extension modules made by **h2xs**. (Some *.ph* values may already be available through the POSIX, Errno, or Fcntl modules.) The **pl2pm** file in the distribution may help in your conversion, but it's just a mechanical process and therefore far from bulletproof. ### Pragmatic Modules They work somewhat like compiler directives (pragmata) in that they tend to affect the compilation of your program, and thus will usually work well only when used within a `"use"`, or `"no"`. Most of these are lexically scoped, so an inner BLOCK may countermand them by saying: ``` no integer; no strict 'refs'; no warnings; ``` which lasts until the end of that BLOCK. Some pragmas are lexically scoped--typically those that affect the `$^H` hints variable. Others affect the current package instead, like `"use vars"` and `"use subs"`, which allow you to predeclare a variables or subroutines within a particular *file* rather than just a block. Such declarations are effective for the entire file for which they were declared. You cannot rescind them with `"no` `vars"` or `"no subs"`. The following pragmas are defined (and have their own documentation). - attributes Get/set subroutine or variable attributes - autodie Replace functions with ones that succeed or die with lexical scope - autodie::exception Exceptions from autodying functions. - autodie::exception::system Exceptions from autodying **system()**. - autodie::hints Provide hints about user subroutines to autodie - autodie::skip Skip a package when throwing autodie exceptions - autouse Postpone load of modules until a function is used - base Establish an ISA relationship with base classes at compile time - bigfloat Transparent big floating point number support for Perl - bigint Transparent big integer support for Perl - bignum Transparent big number support for Perl - bigrat Transparent big rational number support for Perl - blib Use MakeMaker's uninstalled version of a package - builtin Import built-in utility functions - bytes Expose the individual bytes of characters - charnames Access to Unicode character names and named character sequences; also define character names - constant Declare constants - deprecate Perl pragma for deprecating the inclusion of a module in core - diagnostics Produce verbose warning diagnostics - encoding Allows you to write your script in non-ASCII and non-UTF-8 - encoding::warnings Warn on implicit encoding conversions - experimental Experimental features made easy - feature Enable new features - fields Compile-time class fields - filetest Control the filetest permission operators - if `"use"` a Perl module if a condition holds - integer Use integer arithmetic instead of floating point - less Request less of something - lib Manipulate `@INC` at compile time - locale Use or avoid POSIX locales for built-in operations - mro Method Resolution Order - ok Alternative to Test::More::use\_ok - open Set default PerlIO layers for input and output - ops Restrict unsafe operations when compiling - overload Package for overloading Perl operations - overloading Lexically control overloading - parent Establish an ISA relationship with base classes at compile time - re Alter regular expression behaviour - sigtrap Enable simple signal handling - sort Control **sort()** behaviour - stable Experimental features made easy, once we know they're stable - strict Restrict unsafe constructs - subs Predeclare subroutine names - threads Perl interpreter-based threads - threads::shared Perl extension for sharing data structures between threads - utf8 Enable/disable UTF-8 (or UTF-EBCDIC) in source code - vars Predeclare global variable names - version Perl extension for Version Objects - vmsish Control VMS-specific language features - warnings Control optional warnings - warnings::register Warnings import function ### Standard Modules Standard, bundled modules are all expected to behave in a well-defined manner with respect to namespace pollution because they use the Exporter module. See their own documentation for details. It's possible that not all modules listed below are installed on your system. For example, the GDBM\_File module will not be installed if you don't have the gdbm library. - Amiga::ARexx Perl extension for ARexx support - Amiga::Exec Perl extension for low level amiga support - AnyDBM\_File Provide framework for multiple DBMs - App::Cpan Easily interact with CPAN from the command line - App::Prove Implements the `"prove"` command. - App::Prove::State State storage for the `"prove"` command. - App::Prove::State::Result Individual test suite results. - App::Prove::State::Result::Test Individual test results. - Archive::Tar Module for manipulations of tar archives - Archive::Tar::File A subclass for in-memory extracted file from Archive::Tar - Attribute::Handlers Simpler definition of attribute handlers - AutoLoader Load subroutines only on demand - AutoSplit Split a package for autoloading - B The Perl Compiler Backend - B::Concise Walk Perl syntax tree, printing concise info about ops - B::Deparse Perl compiler backend to produce perl code - B::Op\_private OP op\_private flag definitions - B::Showlex Show lexical variables used in functions or files - B::Terse Walk Perl syntax tree, printing terse info about ops - B::Xref Generates cross reference reports for Perl programs - Benchmark Benchmark running times of Perl code - "IO::Socket::IP" Family-neutral IP socket supporting both IPv4 and IPv6 - "Socket" Networking constants and support functions - "Test2::Tools::Refcount" Assert reference counts on objects - CORE Namespace for Perl's core routines - CPAN Query, download and build perl modules from CPAN sites - CPAN::API::HOWTO A recipe book for programming with CPAN.pm - CPAN::Debug Internal debugging for CPAN.pm - CPAN::Distroprefs Read and match distroprefs - CPAN::FirstTime Utility for CPAN::Config file Initialization - CPAN::HandleConfig Internal configuration handling for CPAN.pm - CPAN::Kwalify Interface between CPAN.pm and Kwalify.pm - CPAN::Meta The distribution metadata for a CPAN dist - CPAN::Meta::Converter Convert CPAN distribution metadata structures - CPAN::Meta::Feature An optional feature provided by a CPAN distribution - CPAN::Meta::History History of CPAN Meta Spec changes - CPAN::Meta::History::Meta\_1\_0 Version 1.0 metadata specification for META.yml - CPAN::Meta::History::Meta\_1\_1 Version 1.1 metadata specification for META.yml - CPAN::Meta::History::Meta\_1\_2 Version 1.2 metadata specification for META.yml - CPAN::Meta::History::Meta\_1\_3 Version 1.3 metadata specification for META.yml - CPAN::Meta::History::Meta\_1\_4 Version 1.4 metadata specification for META.yml - CPAN::Meta::Merge Merging CPAN Meta fragments - CPAN::Meta::Prereqs A set of distribution prerequisites by phase and type - CPAN::Meta::Requirements A set of version requirements for a CPAN dist - CPAN::Meta::Requirements::Range A set of version requirements for a CPAN dist - CPAN::Meta::Spec Specification for CPAN distribution metadata - CPAN::Meta::Validator Validate CPAN distribution metadata structures - CPAN::Meta::YAML Read and write a subset of YAML for CPAN Meta files - CPAN::Nox Wrapper around CPAN.pm without using any XS module - CPAN::Plugin Base class for CPAN shell extensions - CPAN::Plugin::Specfile Proof of concept implementation of a trivial CPAN::Plugin - CPAN::Queue Internal queue support for CPAN.pm - CPAN::Tarzip Internal handling of tar archives for CPAN.pm - CPAN::Version Utility functions to compare CPAN versions - Carp Alternative warn and die for modules - Class::Struct Declare struct-like datatypes as Perl classes - Compress::Raw::Bzip2 Low-Level Interface to bzip2 compression library - Compress::Raw::Zlib Low-Level Interface to zlib or zlib-ng compression library - Compress::Zlib Interface to zlib compression library - Config Access Perl configuration information - Config::Extensions Hash lookup of which core extensions were built. - Config::Perl::V Structured data retrieval of perl -V output - Cwd Get pathname of current working directory - DB Programmatic interface to the Perl debugging API - DBM\_Filter Filter DBM keys/values - DBM\_Filter::compress Filter for DBM\_Filter - DBM\_Filter::encode Filter for DBM\_Filter - DBM\_Filter::int32 Filter for DBM\_Filter - DBM\_Filter::null Filter for DBM\_Filter - DBM\_Filter::utf8 Filter for DBM\_Filter - DB\_File Perl5 access to Berkeley DB version 1.x - Data::Dumper Stringified perl data structures, suitable for both printing and `"eval"` - Devel::PPPort Perl/Pollution/Portability - Devel::Peek A data debugging tool for the XS programmer - Devel::SelfStubber Generate stubs for a SelfLoading module - Digest Modules that calculate message digests - Digest::MD5 Perl interface to the MD5 Algorithm - Digest::SHA Perl extension for SHA-1/224/256/384/512 - Digest::base Digest base class - Digest::file Calculate digests of files - DirHandle (obsolete) supply object methods for directory handles - Dumpvalue Provides screen dump of Perl data. - DynaLoader Dynamically load C libraries into Perl code - Encode Character encodings in Perl - Encode::Alias Alias definitions to encodings - Encode::Byte Single Byte Encodings - Encode::CJKConstants Internally used by Encode::??::ISO\_2022\_\* - Encode::CN China-based Chinese Encodings - Encode::CN::HZ Internally used by Encode::CN - Encode::Config Internally used by Encode - Encode::EBCDIC EBCDIC Encodings - Encode::Encoder Object Oriented Encoder - Encode::Encoding Encode Implementation Base Class - Encode::GSM0338 ETSI GSM 03.38 Encoding - Encode::Guess Guesses encoding from data - Encode::JP Japanese Encodings - Encode::JP::H2Z Internally used by Encode::JP::2022\_JP\* - Encode::JP::JIS7 Internally used by Encode::JP - Encode::KR Korean Encodings - Encode::KR::2022\_KR Internally used by Encode::KR - Encode::MIME::Header MIME encoding for an unstructured email header - Encode::MIME::Name Internally used by Encode - Encode::PerlIO A detailed document on Encode and PerlIO - Encode::Supported Encodings supported by Encode - Encode::Symbol Symbol Encodings - Encode::TW Taiwan-based Chinese Encodings - Encode::Unicode Various Unicode Transformation Formats - Encode::Unicode::UTF7 UTF-7 encoding - English Use nice English (or awk) names for ugly punctuation variables - Env Perl module that imports environment variables as scalars or arrays - Errno System errno constants - Exporter Implements default import method for modules - Exporter::Heavy Exporter guts - ExtUtils::CBuilder Compile and link C code for Perl modules - ExtUtils::CBuilder::Platform::Windows Builder class for Windows platforms - ExtUtils::Command Utilities to replace common UNIX commands in Makefiles etc. - ExtUtils::Command::MM Commands for the MM's to use in Makefiles - ExtUtils::Constant Generate XS code to import C header constants - ExtUtils::Constant::Base Base class for ExtUtils::Constant objects - ExtUtils::Constant::Utils Helper functions for ExtUtils::Constant - ExtUtils::Constant::XS Generate C code for XS modules' constants. - ExtUtils::Embed Utilities for embedding Perl in C/C++ applications - ExtUtils::Install Install files from here to there - ExtUtils::Installed Inventory management of installed modules - ExtUtils::Liblist Determine libraries to use and how to use them - ExtUtils::MM OS adjusted ExtUtils::MakeMaker subclass - ExtUtils::MM\_AIX AIX specific subclass of ExtUtils::MM\_Unix - ExtUtils::MM\_Any Platform-agnostic MM methods - ExtUtils::MM\_BeOS Methods to override UN\*X behaviour in ExtUtils::MakeMaker - ExtUtils::MM\_Cygwin Methods to override UN\*X behaviour in ExtUtils::MakeMaker - ExtUtils::MM\_DOS DOS specific subclass of ExtUtils::MM\_Unix - ExtUtils::MM\_Darwin Special behaviors for OS X - ExtUtils::MM\_MacOS Once produced Makefiles for MacOS Classic - ExtUtils::MM\_NW5 Methods to override UN\*X behaviour in ExtUtils::MakeMaker - ExtUtils::MM\_OS2 Methods to override UN\*X behaviour in ExtUtils::MakeMaker - ExtUtils::MM\_OS390 OS390 specific subclass of ExtUtils::MM\_Unix - ExtUtils::MM\_QNX QNX specific subclass of ExtUtils::MM\_Unix - ExtUtils::MM\_UWIN U/WIN specific subclass of ExtUtils::MM\_Unix - ExtUtils::MM\_Unix Methods used by ExtUtils::MakeMaker - ExtUtils::MM\_VMS Methods to override UN\*X behaviour in ExtUtils::MakeMaker - ExtUtils::MM\_VOS VOS specific subclass of ExtUtils::MM\_Unix - ExtUtils::MM\_Win32 Methods to override UN\*X behaviour in ExtUtils::MakeMaker - ExtUtils::MM\_Win95 Method to customize MakeMaker for Win9X - ExtUtils::MY ExtUtils::MakeMaker subclass for customization - ExtUtils::MakeMaker Create a module Makefile - ExtUtils::MakeMaker::Config Wrapper around Config.pm - ExtUtils::MakeMaker::FAQ Frequently Asked Questions About MakeMaker - ExtUtils::MakeMaker::Locale Bundled Encode::Locale - ExtUtils::MakeMaker::Tutorial Writing a module with MakeMaker - ExtUtils::Manifest Utilities to write and check a MANIFEST file - ExtUtils::Miniperl Write the C code for miniperlmain.c and perlmain.c - ExtUtils::Mkbootstrap Make a bootstrap file for use by DynaLoader - ExtUtils::Mksymlists Write linker options files for dynamic extension - ExtUtils::PL2Bat Batch file creation to run perl scripts on Windows - ExtUtils::Packlist Manage .packlist files - ExtUtils::ParseXS Converts Perl XS code into C code - ExtUtils::ParseXS::Constants Initialization values for some globals - ExtUtils::ParseXS::Eval Clean package to evaluate code in - ExtUtils::ParseXS::Utilities Subroutines used with ExtUtils::ParseXS - ExtUtils::Typemaps Read/Write/Modify Perl/XS typemap files - ExtUtils::Typemaps::Cmd Quick commands for handling typemaps - ExtUtils::Typemaps::InputMap Entry in the INPUT section of a typemap - ExtUtils::Typemaps::OutputMap Entry in the OUTPUT section of a typemap - ExtUtils::Typemaps::Type Entry in the TYPEMAP section of a typemap - ExtUtils::XSSymSet Keep sets of symbol names palatable to the VMS linker - ExtUtils::testlib Add blib/\* directories to `@INC` - Fatal Replace functions with equivalents which succeed or die - Fcntl Various flag constants and helper functions from C's fcntl.h - File::Basename Parse file paths into directory, filename and suffix. - File::Compare Compare files or filehandles - File::Copy Copy files or filehandles - File::DosGlob DOS like globbing and then some - File::Fetch A generic file fetching mechanism - File::Find Traverse a directory tree. - File::Glob Perl extension for BSD glob routine - File::GlobMapper Extend File Glob to Allow Input and Output Files - File::Path Create or remove directory trees - File::Spec Portably perform operations on file names - File::Spec::AmigaOS File::Spec for AmigaOS - File::Spec::Cygwin Methods for Cygwin file specs - File::Spec::Epoc Methods for Epoc file specs - File::Spec::Functions Portably perform operations on file names - File::Spec::Mac File::Spec for Mac OS (Classic) - File::Spec::OS2 Methods for OS/2 file specs - File::Spec::Unix File::Spec for Unix, base for other File::Spec modules - File::Spec::VMS Methods for VMS file specs - File::Spec::Win32 Methods for Win32 file specs - File::Temp Return name and handle of a temporary file safely - File::stat By-name interface to Perl's built-in **stat()** functions - FileCache Keep more files open than the system permits - FileHandle Supply object methods for filehandles - Filter::Simple Simplified source filtering - Filter::Util::Call Perl Source Filter Utility Module - FindBin Locate directory of original Perl script - GDBM\_File Perl5 access to the gdbm library. - Getopt::Long Extended processing of command line options - Getopt::Long::Parser Getopt::Long object oriented interface - Getopt::Std Process single-character switches with switch clustering - HTTP::Tiny A small, simple, correct HTTP/1.1 client - Hash::Util A selection of general-utility hash subroutines - Hash::Util::FieldHash Support for Inside-Out Classes - I18N::Collate Compare 8-bit scalar data according to the current locale - I18N::LangTags Functions for dealing with RFC3066-style language tags - I18N::LangTags::Detect Detect the user's language preferences - I18N::LangTags::List Tags and names for human languages - I18N::Langinfo Query locale information - IO Load various IO modules - IO::Compress::Base Base Class for IO::Compress modules - IO::Compress::Bzip2 Write bzip2 files/buffers - IO::Compress::Deflate Write RFC 1950 files/buffers - IO::Compress::FAQ Frequently Asked Questions about IO::Compress - IO::Compress::Gzip Write RFC 1952 files/buffers - IO::Compress::RawDeflate Write RFC 1951 files/buffers - IO::Compress::Zip Write zip files/buffers - IO::Dir Supply object methods for directory handles - IO::File Supply object methods for filehandles - IO::Handle Supply object methods for I/O handles - IO::Pipe Supply object methods for pipes - IO::Poll Object interface to system poll call - IO::Seekable Supply seek based methods for I/O objects - IO::Select OO interface to 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 - IO::Uncompress::AnyInflate Uncompress zlib-based (zip, gzip) file/buffer - IO::Uncompress::AnyUncompress Uncompress gzip, zip, bzip2, zstd, xz, lzma, lzip, lzf or lzop file/buffer - IO::Uncompress::Base Base Class for IO::Uncompress modules - IO::Uncompress::Bunzip2 Read bzip2 files/buffers - IO::Uncompress::Gunzip Read RFC 1952 files/buffers - IO::Uncompress::Inflate Read RFC 1950 files/buffers - IO::Uncompress::RawInflate Read RFC 1951 files/buffers - IO::Uncompress::Unzip Read zip files/buffers - IO::Zlib IO:: style interface to Compress::Zlib - IPC::Cmd Finding and running system commands made easy - IPC::Msg SysV Msg IPC object class - IPC::Open2 Open a process for both reading and writing using **open2()** - IPC::Open3 Open a process for reading, writing, and error handling using **open3()** - IPC::Semaphore SysV Semaphore IPC object class - IPC::SharedMem SysV Shared Memory IPC object class - IPC::SysV System V IPC constants and system calls - Internals Reserved special namespace for internals related functions - JSON::PP JSON::XS compatible pure-Perl module. - JSON::PP::Boolean Dummy module providing JSON::PP::Boolean - List::Util A selection of general-utility list subroutines - List::Util::XS Indicate if List::Util was compiled with a C compiler - Locale::Maketext Framework for localization - Locale::Maketext::Cookbook Recipes for using Locale::Maketext - Locale::Maketext::Guts Deprecated module to load Locale::Maketext utf8 code - Locale::Maketext::GutsLoader Deprecated module to load Locale::Maketext utf8 code - Locale::Maketext::Simple Simple interface to Locale::Maketext::Lexicon - Locale::Maketext::TPJ13 Article about software localization - MIME::Base64 Encoding and decoding of base64 strings - MIME::QuotedPrint Encoding and decoding of quoted-printable strings - Math::BigFloat Arbitrary size floating point math package - Math::BigInt Arbitrary size integer math package - Math::BigInt::Calc Pure Perl module to support Math::BigInt - Math::BigInt::FastCalc Math::BigInt::Calc with some XS for more speed - Math::BigInt::Lib Virtual parent class for Math::BigInt libraries - Math::BigRat Arbitrary size rational number math package - Math::Complex Complex numbers and associated mathematical functions - Math::Trig Trigonometric functions - Memoize Make functions faster by trading space for time - Memoize::AnyDBM\_File Glue to provide EXISTS for AnyDBM\_File for Storable use - Memoize::Expire Plug-in module for automatic expiration of memoized values - Memoize::NDBM\_File Glue to provide EXISTS for NDBM\_File for Storable use - Memoize::SDBM\_File DEPRECATED compability shim - Memoize::Storable Store Memoized data in Storable database - Module::CoreList What modules shipped with versions of perl - Module::CoreList::Utils What utilities shipped with versions of perl - Module::Load Runtime require of both modules and files - Module::Load::Conditional Looking up module information / loading at runtime - Module::Loaded Mark modules as loaded or unloaded - Module::Metadata Gather package and POD information from perl module files - NDBM\_File Tied access to ndbm files - NEXT Provide a pseudo-class NEXT (et al) that allows method redispatch - Net::Cmd Network Command class (as used by FTP, SMTP etc) - Net::Config Local configuration data for libnet - Net::Domain Attempt to evaluate the current host's internet name and domain - Net::FTP FTP Client class - Net::FTP::dataconn FTP Client data connection class - Net::NNTP NNTP Client class - Net::Netrc OO interface to users netrc file - Net::POP3 Post Office Protocol 3 Client class (RFC1939) - Net::Ping Check a remote host for reachability - Net::SMTP Simple Mail Transfer Protocol Client - Net::Time Time and daytime network client interface - Net::hostent By-name interface to Perl's built-in gethost\*() functions - Net::libnetFAQ Libnet Frequently Asked Questions - Net::netent By-name interface to Perl's built-in getnet\*() functions - Net::protoent By-name interface to Perl's built-in getproto\*() functions - Net::servent By-name interface to Perl's built-in getserv\*() functions - O Generic interface to Perl Compiler backends - ODBM\_File Tied access to odbm files - Opcode Disable named opcodes when compiling perl code - POSIX Perl interface to IEEE Std 1003.1 - Params::Check A generic input parsing/checking mechanism. - Parse::CPAN::Meta Parse META.yml and META.json CPAN metadata files - Perl::OSType Map Perl operating system names to generic types - PerlIO On demand loader for PerlIO layers and root of PerlIO::\* name space - PerlIO::encoding Encoding layer - PerlIO::mmap Memory mapped IO - PerlIO::scalar In-memory IO, scalar IO - PerlIO::via Helper class for PerlIO layers implemented in perl - PerlIO::via::QuotedPrint PerlIO layer for quoted-printable strings - Pod::Checker Check pod documents for syntax errors - Pod::Escapes For resolving Pod E\<...\> sequences - Pod::Functions Group Perl's functions a la perlfunc.pod - Pod::Html Module to convert pod files to HTML - Pod::Html::Util Helper functions for Pod-Html - Pod::Man Convert POD data to formatted \*roff input - Pod::ParseLink Parse an L\<\> formatting code in POD text - Pod::Perldoc Look up Perl documentation in Pod format. - Pod::Perldoc::BaseTo Base for Pod::Perldoc formatters - Pod::Perldoc::GetOptsOO Customized option parser for Pod::Perldoc - Pod::Perldoc::ToANSI Render Pod with ANSI color escapes - Pod::Perldoc::ToChecker Let Perldoc check Pod for errors - Pod::Perldoc::ToMan Let Perldoc render Pod as man pages - Pod::Perldoc::ToNroff Let Perldoc convert Pod to nroff - Pod::Perldoc::ToPod Let Perldoc render Pod as ... Pod! - Pod::Perldoc::ToRtf Let Perldoc render Pod as RTF - Pod::Perldoc::ToTerm Render Pod with terminal escapes - Pod::Perldoc::ToText Let Perldoc render Pod as plaintext - Pod::Perldoc::ToTk Let Perldoc use Tk::Pod to render Pod - Pod::Perldoc::ToXml Let Perldoc render Pod as XML - Pod::Simple Framework for parsing Pod - Pod::Simple::Checker Check the Pod syntax of a document - Pod::Simple::Debug Put Pod::Simple into trace/debug mode - Pod::Simple::DumpAsText Dump Pod-parsing events as text - Pod::Simple::DumpAsXML Turn Pod into XML - Pod::Simple::HTML Convert Pod to HTML - Pod::Simple::HTMLBatch Convert several Pod files to several HTML files - Pod::Simple::JustPod Just the Pod, the whole Pod, and nothing but the Pod - Pod::Simple::LinkSection Represent "section" attributes of L codes - Pod::Simple::Methody Turn Pod::Simple events into method calls - Pod::Simple::PullParser A pull-parser interface to parsing Pod - Pod::Simple::PullParserEndToken End-tokens from Pod::Simple::PullParser - Pod::Simple::PullParserStartToken Start-tokens from Pod::Simple::PullParser - Pod::Simple::PullParserTextToken Text-tokens from Pod::Simple::PullParser - Pod::Simple::PullParserToken Tokens from Pod::Simple::PullParser - Pod::Simple::RTF Format Pod as RTF - Pod::Simple::Search Find POD documents in directory trees - Pod::Simple::SimpleTree Parse Pod into a simple parse tree - Pod::Simple::Subclassing Write a formatter as a Pod::Simple subclass - Pod::Simple::Text Format Pod as plaintext - Pod::Simple::TextContent Get the text content of Pod - Pod::Simple::XHTML Format Pod as validating XHTML - Pod::Simple::XMLOutStream Turn Pod into XML - Pod::Text Convert POD data to formatted text - Pod::Text::Color Convert POD data to formatted color ASCII text - Pod::Text::Overstrike Convert POD data to formatted overstrike text - Pod::Text::Termcap Convert POD data to ASCII text with format escapes - Pod::Usage Extracts POD documentation and shows usage information - SDBM\_File Tied access to sdbm files - Safe Compile and execute code in restricted compartments - Scalar::Util A selection of general-utility scalar subroutines - Search::Dict Look - search for key in dictionary file - SelectSaver Save and restore selected file handle - SelfLoader Load functions only on demand - Storable Persistence for Perl data structures - Sub::Util A selection of utility subroutines for subs and CODE references - Symbol Manipulate Perl symbols and their names - Sys::Hostname Try every conceivable way to get hostname - Sys::Syslog Perl interface to the UNIX [**syslog**(3)](/syslog/3.md) calls - Sys::Syslog::Win32 Win32 support for Sys::Syslog - TAP::Base Base class that provides common functionality to TAP::Parser - TAP::Formatter::Base Base class for harness output delegates - TAP::Formatter::Color Run Perl test scripts with color - TAP::Formatter::Console Harness output delegate for default console output - TAP::Formatter::Console::ParallelSession Harness output delegate for parallel console output - TAP::Formatter::Console::Session Harness output delegate for default console output - TAP::Formatter::File Harness output delegate for file output - TAP::Formatter::File::Session Harness output delegate for file output - TAP::Formatter::Session Abstract base class for harness output delegate - TAP::Harness Run test scripts with statistics - TAP::Harness::Env Parsing harness related environmental variables where appropriate - TAP::Object Base class that provides common functionality to all `"TAP::*"` modules - TAP::Parser Parse TAP output - TAP::Parser::Aggregator Aggregate TAP::Parser results - TAP::Parser::Grammar A grammar for the Test Anything Protocol. - TAP::Parser::Iterator Base class for TAP source iterators - TAP::Parser::Iterator::Array Iterator for array-based TAP sources - TAP::Parser::Iterator::Process Iterator for process-based TAP sources - TAP::Parser::Iterator::Stream Iterator for filehandle-based TAP sources - TAP::Parser::IteratorFactory Figures out which SourceHandler objects to use for a given Source - TAP::Parser::Multiplexer Multiplex multiple TAP::Parsers - TAP::Parser::Result Base class for TAP::Parser output objects - TAP::Parser::Result::Bailout Bailout result token. - TAP::Parser::Result::Comment Comment result token. - TAP::Parser::Result::Plan Plan result token. - TAP::Parser::Result::Pragma TAP pragma token. - TAP::Parser::Result::Test Test result token. - TAP::Parser::Result::Unknown Unknown result token. - TAP::Parser::Result::Version TAP syntax version token. - TAP::Parser::Result::YAML YAML result token. - TAP::Parser::ResultFactory Factory for creating TAP::Parser output objects - TAP::Parser::Scheduler Schedule tests during parallel testing - TAP::Parser::Scheduler::Job A single testing job. - TAP::Parser::Scheduler::Spinner A no-op job. - TAP::Parser::Source A TAP source & meta data about it - TAP::Parser::SourceHandler Base class for different TAP source handlers - TAP::Parser::SourceHandler::Executable Stream output from an executable TAP source - TAP::Parser::SourceHandler::File Stream TAP from a text file. - TAP::Parser::SourceHandler::Handle Stream TAP from an IO::Handle or a GLOB. - TAP::Parser::SourceHandler::Perl Stream TAP from a Perl executable - TAP::Parser::SourceHandler::RawTAP Stream output from raw TAP in a scalar/array ref. - TAP::Parser::YAMLish::Reader Read YAMLish data from iterator - TAP::Parser::YAMLish::Writer Write YAMLish data - Term::ANSIColor Color screen output using ANSI escape sequences - Term::Cap Perl termcap interface - Term::Complete Perl word completion module - Term::ReadLine Perl interface to various `"readline"` packages. - Term::Table Format a header and rows into a table - Term::Table::Cell Representation of a cell in a table. - Term::Table::CellStack Combine several cells into one (vertical) - Term::Table::HashBase Build hash based classes. - Term::Table::LineBreak Break up lines for use in tables. - Term::Table::Util Utilities for Term::Table. - Test Provides a simple framework for writing test scripts - Test2 Framework for writing test tools that all work together. - Test2::API Primary interface for writing Test2 based testing tools. - Test2::API::Breakage What breaks at what version - Test2::API::Context Object to represent a testing context. - Test2::API::Instance Object used by Test2::API under the hood - Test2::API::InterceptResult Representation of a list of events. - Test2::API::InterceptResult::Event Representation of an event for use in - Test2::API::InterceptResult::Hub Hub used by InterceptResult. - Test2::API::InterceptResult::Squasher Encapsulation of the algorithm that - Test2::API::Stack Object to manage a stack of Test2::Hub - Test2::AsyncSubtest Object representing an async subtest. - Test2::AsyncSubtest::Event::Attach Event to attach a subtest to the parent. - Test2::AsyncSubtest::Event::Detach Event to detach a subtest from the parent. - Test2::AsyncSubtest::Hub Hub used by async subtests. - Test2::Bundle Documentation for bundles. - Test2::Bundle::Extended Old name for Test2::V0 - Test2::Bundle::More ALMOST a drop-in replacement for Test::More. - Test2::Bundle::Simple ALMOST a drop-in replacement for Test::Simple. - Test2::Compare Test2 extension for writing deep comparison tools. - Test2::Compare::Array Internal representation of an array comparison. - Test2::Compare::Bag Internal representation of a bag comparison. - Test2::Compare::Base Base class for comparison classes. - Test2::Compare::Bool Compare two values as booleans - Test2::Compare::Custom Custom field check for comparisons. - Test2::Compare::DeepRef Ref comparison - Test2::Compare::Delta Representation of differences between nested data - Test2::Compare::Event Event specific Object subclass. - Test2::Compare::EventMeta Meta class for events in deep comparisons - Test2::Compare::Float Compare two values as numbers with tolerance. - Test2::Compare::Hash Representation of a hash in a deep comparison. - Test2::Compare::Isa Check if the value is an instance of the class. - Test2::Compare::Meta Check library for meta-checks - Test2::Compare::Negatable Poor mans 'role' for compare objects that can be negated. - Test2::Compare::Number Compare two values as numbers - Test2::Compare::Object Representation of an object during deep - Test2::Compare::OrderedSubset Internal representation of an ordered subset. - Test2::Compare::Pattern Use a pattern to validate values in a deep - Test2::Compare::Ref Ref comparison - Test2::Compare::Regex Regex direct comparison - Test2::Compare::Scalar Representation of a Scalar Ref in deep - Test2::Compare::Set Allows a field to be matched against a set of - Test2::Compare::String Compare two values as strings - Test2::Compare::Undef Check that something is undefined - Test2::Compare::Wildcard Placeholder check. - Test2::Event Base class for events - Test2::Event::Bail Bailout! - Test2::Event::Diag Diag event type - Test2::Event::Encoding Set the encoding for the output stream - Test2::Event::Exception Exception event - Test2::Event::Fail Event for a simple failed assertion - Test2::Event::Generic Generic event type. - Test2::Event::Note Note event type - Test2::Event::Ok Ok event type - Test2::Event::Pass Event for a simple passing assertion - Test2::Event::Plan The event of a plan - Test2::Event::Skip Skip event type - Test2::Event::Subtest Event for subtest types - Test2::Event::TAP::Version Event for TAP version. - Test2::Event::V2 Second generation event. - Test2::Event::Waiting Tell all procs/threads it is time to be done - Test2::EventFacet Base class for all event facets. - Test2::EventFacet::About Facet with event details. - Test2::EventFacet::Amnesty Facet for assertion amnesty. - Test2::EventFacet::Assert Facet representing an assertion. - Test2::EventFacet::Control Facet for hub actions and behaviors. - Test2::EventFacet::Error Facet for errors that need to be shown. - Test2::EventFacet::Hub Facet for the hubs an event passes through. - Test2::EventFacet::Info Facet for information a developer might care about. - Test2::EventFacet::Info::Table Intermediary representation of a table. - Test2::EventFacet::Meta Facet for meta-data - Test2::EventFacet::Parent Facet for events contains other events - Test2::EventFacet::Plan Facet for setting the plan - Test2::EventFacet::Render Facet that dictates how to render an event. - Test2::EventFacet::Trace Debug information for events - Test2::Formatter Namespace for formatters. - Test2::Formatter::TAP Standard TAP formatter - Test2::Hub The conduit through which all events flow. - Test2::Hub::Interceptor Hub used by interceptor to grab results. - Test2::Hub::Interceptor::Terminator Exception class used by - Test2::Hub::Subtest Hub used by subtests - Test2::IPC Turn on IPC for threading or forking support. - Test2::IPC::Driver Base class for Test2 IPC drivers. - Test2::IPC::Driver::Files Temp dir + Files concurrency model. - Test2::Manual Documentation hub for Test2 and Test2-Suite. - Test2::Manual::Anatomy The hub for documentation of the inner workings of - Test2::Manual::Anatomy::API Internals documentation for the API. - Test2::Manual::Anatomy::Context Internals documentation for the Context - Test2::Manual::Anatomy::Event The internals of events - Test2::Manual::Anatomy::Hubs Internals documentation for the hub stack, and - Test2::Manual::Anatomy::IPC Manual for the IPC system. - Test2::Manual::Anatomy::Utilities Overview of utilities for Test2. - Test2::Manual::Concurrency Documentation for Concurrency support. - Test2::Manual::Contributing How to contribute to the Test2 project. - Test2::Manual::EndToEnd Overview of Test2 from load to finish. - Test2::Manual::Testing Hub for documentation about writing tests with Test2. - Test2::Manual::Testing::Introduction Introduction to testing with Test2. - Test2::Manual::Testing::Migrating How to migrate existing tests from - Test2::Manual::Testing::Planning The many ways to set a plan. - Test2::Manual::Testing::Todo Tutorial for marking tests as TODO. - Test2::Manual::Tooling Manual page for tool authors. - Test2::Manual::Tooling::FirstTool Write your first tool with Test2. - Test2::Manual::Tooling::Formatter How to write a custom formatter, in our - Test2::Manual::Tooling::Nesting Tutorial for using other tools within your - Test2::Manual::Tooling::Plugin::TestExit How to safely add pre-exit - Test2::Manual::Tooling::Plugin::TestingDone Run code when the test file is - Test2::Manual::Tooling::Plugin::ToolCompletes How to add behaviors that occur - Test2::Manual::Tooling::Plugin::ToolStarts How to add behaviors that occur - Test2::Manual::Tooling::Subtest How to implement a tool that makes use of - Test2::Manual::Tooling::TestBuilder This section maps Test::Builder methods - Test2::Manual::Tooling::Testing Tutorial on how to test your testing tools. - Test2::Mock Module for managing mocked classes and instances. - Test2::Plugin Documentation for plugins - Test2::Plugin::BailOnFail Automatically bail out of testing on the first test - Test2::Plugin::DieOnFail Automatically die on the first test failure. - Test2::Plugin::ExitSummary Add extra diagnostics on failure at the end of the - Test2::Plugin::SRand Control the random seed for more controlled test - Test2::Plugin::Times Output timing data at the end of the test. - Test2::Plugin::UTF8 Test2 plugin to test with utf8. - Test2::Require Base class and documentation for skip-unless type test - Test2::Require::AuthorTesting Only run a test when the AUTHOR\_TESTING - Test2::Require::AutomatedTesting Only run a test when the AUTOMATED\_TESTING - Test2::Require::EnvVar Only run a test when a specific environment variable - Test2::Require::ExtendedTesting Only run a test when the EXTENDED\_TESTING - Test2::Require::Fork Skip a test file unless the system supports forking - Test2::Require::Module Skip tests if certain packages are not installed, or - Test2::Require::NonInteractiveTesting Only run a test when the NONINTERACTIVE\_TESTING - Test2::Require::Perl Skip the test unless the necessary version of Perl is - Test2::Require::RealFork Skip a test file unless the system supports true - Test2::Require::ReleaseTesting Only run a test when the RELEASE\_TESTING - Test2::Require::Threads Skip a test file unless the system supports threading - Test2::Suite Distribution with a rich set of tools built upon the Test2 - Test2::Todo TODO extension for Test2. - Test2::Tools Documentation for Tools. - Test2::Tools::AsyncSubtest Tools for writing async subtests. - Test2::Tools::Basic Test2 implementation of the basic testing tools. - Test2::Tools::Class Test2 implementation of the tools for testing classes. - Test2::Tools::ClassicCompare Classic (Test::More style) comparison tools. - Test2::Tools::Compare Tools for comparing deep data structures. - Test2::Tools::Defer Write tests that get executed at a later time - Test2::Tools::Encoding Tools for managing the encoding of Test2 based - Test2::Tools::Event Tools for generating test events. - Test2::Tools::Exception Test2 based tools for checking exceptions - Test2::Tools::Exports Tools for validating exporters. - Test2::Tools::GenTemp Tool for generating a populated temp directory. - Test2::Tools::Grab Temporarily intercept all events without adding a scope - Test2::Tools::Mock Class/Instance mocking for Test2. - Test2::Tools::Ref Tools for validating references. - Test2::Tools::Spec RSPEC implementation on top of Test2::Workflow - Test2::Tools::Subtest Tools for writing subtests - Test2::Tools::Target Alias the testing target package. - Test2::Tools::Tester Tools to help you test other testing tools. - Test2::Tools::Tiny Tiny set of tools for unfortunate souls who cannot use - Test2::Tools::Warnings Tools to verify warnings. - Test2::Transition Transition notes when upgrading to Test2 - Test2::Util Tools used by Test2 and friends. - Test2::Util::ExternalMeta Allow third party tools to safely attach meta-data - Test2::Util::Facets2Legacy Convert facet data to the legacy event API. - Test2::Util::Grabber Object used to temporarily intercept all events. - Test2::Util::Guard Inline copy of Scope::Guard - Test2::Util::HashBase Build hash based classes. - Test2::Util::Importer Inline copy of Importer. - Test2::Util::Ref Tools for inspecting or manipulating references. - Test2::Util::Stash Utilities for manipulating stashes and globs. - Test2::Util::Sub Tools for inspecting and manipulating subs. - Test2::Util::Table Format a header and rows into a table - Test2::Util::Table::LineBreak Break up lines for use in tables. - Test2::Util::Times Format timing/benchmark information. - Test2::Util::Trace Legacy wrapper fro Test2::EventFacet::Trace. - Test2::V0 0Th edition of the Test2 recommended bundle. - Test2::Workflow A test workflow is a way of structuring tests using - Test2::Workflow::BlockBase Base class for all workflow blocks. - Test2::Workflow::Build Represents a build in progress. - Test2::Workflow::Runner Runs the workflows. - Test2::Workflow::Task Encapsulation of a Task - Test2::Workflow::Task::Action Encapsulation of an action. - Test2::Workflow::Task::Group Encapsulation of a group (describe). - Test::Builder Backend for building test libraries - Test::Builder::Formatter Test::Builder subclass of Test2::Formatter::TAP - Test::Builder::IO::Scalar A copy of IO::Scalar for Test::Builder - Test::Builder::Module Base class for test modules - Test::Builder::Tester Test testsuites that have been built with - Test::Builder::Tester::Color Turn on colour in Test::Builder::Tester - Test::Builder::TodoDiag Test::Builder subclass of Test2::Event::Diag - Test::Harness Run Perl standard test scripts with statistics - Test::Harness::Beyond Beyond make test - Test::More Yet another framework for writing test scripts - Test::Simple Basic utilities for writing tests. - Test::Tester Ease testing test modules built with Test::Builder - Test::Tester::Capture Help testing test modules built with Test::Builder - Test::Tester::CaptureRunner Help testing test modules built with Test::Builder - Test::Tutorial A tutorial about writing really basic tests - Test::use::ok Alternative to Test::More::use\_ok - Text::Abbrev Abbrev - create an abbreviation table from a list - Text::Balanced Extract delimited text sequences from strings. - Text::ParseWords Parse text into an array of tokens or array of arrays - Text::Tabs Expand and unexpand tabs like unix [**expand**(1)](/expand/1.md) and [**unexpand**(1)](/unexpand/1.md) - Text::Wrap Line wrapping to form simple paragraphs - Thread Manipulate threads in Perl (for old code only) - Thread::Queue Thread-safe queues - Thread::Semaphore Thread-safe semaphores - Tie::Array Base class for tied arrays - Tie::File Access the lines of a disk file via a Perl array - Tie::Handle Base class definitions for tied handles - Tie::Hash Base class definitions for tied hashes - Tie::Hash::NamedCapture Named regexp capture buffers - Tie::Memoize Add data to hash when needed - Tie::RefHash Use references as hash keys - Tie::Scalar Base class definitions for tied scalars - Tie::StdHandle Base class definitions for tied handles - Tie::SubstrHash Fixed-table-size, fixed-key-length hashing - Time::HiRes High resolution alarm, sleep, gettimeofday, interval timers - Time::Local Efficiently compute time from local and GMT time - Time::Piece Object Oriented time objects - Time::Seconds A simple API to convert seconds to other date values - Time::gmtime By-name interface to Perl's built-in **gmtime()** function - Time::localtime By-name interface to Perl's built-in **localtime()** function - Time::tm Internal object used by Time::gmtime and Time::localtime - UNIVERSAL Base class for ALL classes (blessed references) - Unicode::Collate Unicode Collation Algorithm - Unicode::Collate::CJK::Big5 Weighting CJK Unified Ideographs - Unicode::Collate::CJK::GB2312 Weighting CJK Unified Ideographs - Unicode::Collate::CJK::JISX0208 Weighting JIS KANJI for Unicode::Collate - Unicode::Collate::CJK::Korean Weighting CJK Unified Ideographs - Unicode::Collate::CJK::Pinyin Weighting CJK Unified Ideographs - Unicode::Collate::CJK::Stroke Weighting CJK Unified Ideographs - Unicode::Collate::CJK::Zhuyin Weighting CJK Unified Ideographs - Unicode::Collate::Locale Linguistic tailoring for DUCET via Unicode::Collate - Unicode::Normalize Unicode Normalization Forms - Unicode::UCD Unicode character database - User::grent By-name interface to Perl's built-in getgr\*() functions - User::pwent By-name interface to Perl's built-in getpw\*() functions - VMS::DCLsym Perl extension to manipulate DCL symbols - VMS::Filespec Convert between VMS and Unix file specification syntax - VMS::Stdio Standard I/O functions via VMS extensions - Win32 Interfaces to some Win32 API Functions - Win32API::File Low-level access to Win32 system API calls for files/dirs. - Win32CORE Win32 CORE function stubs - XS::APItest Test the perl C API - XS::Typemap Module to test the XS typemaps distributed with perl - XSLoader Dynamically load C libraries into Perl code - autodie::Scope::Guard Wrapper class for calling subs at end of scope - autodie::Scope::GuardStack Hook stack for managing scopes via %^H - autodie::Util Internal Utility subroutines for autodie and Fatal - version::Internals Perl extension for Version Objects To find 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 `@INC` from being populated by `"PERL5LIB"`, `"PERLLIB"`, and `"PERL_USE_UNSAFE_INC"`.) They should all have their own documentation installed and accessible via your system [**man**(1)](/man/1.md) command. If you do not have a **find** program, you can use the Perl **find2perl** program instead, which generates Perl code as output you can run through perl. If you have a **man** program but it doesn't find your modules, you'll have to fix your manpath. See perl for details. If you have no system **man** command, you might try the **perldoc** program. Note also that the command `"perldoc perllocal"` gives you a (possibly incomplete) list of the modules that have been further installed on your system. (The perllocal.pod file is updated by the standard MakeMaker install process.) ### Extension Modules Extension modules are written in C (or a mix of Perl and C). They are usually dynamically loaded into Perl if and when you need them, but may also be linked in statically. Supported extension modules include Socket, Fcntl, and POSIX. Many popular C extension modules do not come bundled (at least, not completely) due to their sizes, volatility, or simply lack of time for adequate testing and configuration across the multitude of platforms on which Perl was beta-tested. You are encouraged to look for them on CPAN (described below), or using web search engines like Google or DuckDuckGo. ## CPAN CPAN stands for Comprehensive Perl Archive Network; it's a globally replicated trove of Perl materials, including documentation, style guides, tricks and traps, alternate ports to non-Unix systems and occasional binary distributions for these. Search engines for CPAN can be found at https://www.cpan.org/ Most importantly, CPAN includes around a thousand unbundled modules, some of which require a C compiler to build. Major categories of modules are: - • Language Extensions and Documentation Tools - • Development Support - • Operating System Interfaces - • Networking, Device Control (modems) and InterProcess Communication - • Data Types and Data Type Utilities - • Database Interfaces - • User Interfaces - • Interfaces to / Emulations of Other Programming Languages - • File Names, File Systems and File Locking (see also File Handles) - • String Processing, Language Text Processing, Parsing, and Searching - • Option, Argument, Parameter, and Configuration File Processing - • Internationalization and Locale - • Authentication, Security, and Encryption - • World Wide Web, HTML, HTTP, CGI, MIME - • Server and Daemon Utilities - • Archiving and Compression - • Images, Pixmap and Bitmap Manipulation, Drawing, and Graphing - • Mail and Usenet News - • Control Flow Utilities (callbacks and exceptions etc) - • File Handle and Input/Output Stream Utilities - • Miscellaneous Modules You can find the CPAN online at \ ## 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, perlobj, and AutoLoader for details about the AUTOLOAD mechanism. ### Guidelines for Module Creation - • Do similar modules already exist in some form? If so, please try to reuse the existing modules either in whole or by inheriting useful features into a new class. If this is not practical try to get together with the module authors to work on extending or enhancing the functionality of the existing modules. A perfect example is the plethora of packages in perl4 for dealing with command line options. If you are writing a module to expand an already existing set of modules, please coordinate with the author of the package. It helps if you follow the same naming scheme and module interaction scheme as the original author. - • Try to design the new module to be easy to extend and reuse. Try to `"use warnings;"` (or `"use warnings qw(...);"`). Remember that you can add `"no warnings qw(...);"` to individual blocks of code that need less warnings. Use blessed references. Use the two argument form of bless to bless into the class name given as the first parameter of the constructor, e.g.,: ``` sub new { my $class = shift; return bless {}, $class; } ``` or even this if you'd like it to be used as either a static or a virtual method. ``` sub new { my $self = shift; my $class = ref($self) || $self; return bless {}, $class; } ``` Pass arrays as references so more parameters can be added later (it's also faster). Convert functions into methods where appropriate. Split large methods into smaller more flexible ones. Inherit methods from other modules if appropriate. Avoid class name tests like: `"die "Invalid" unless ref $ref eq 'FOO'"`. Generally you can delete the `"eq 'FOO'"` part with no harm at all. Let the objects look after themselves! Generally, avoid hard-wired class names as far as possible. Avoid `"$r->Class::func()"` where using `"@ISA=qw(... Class ...)"` and `"$r->func()"` would work. 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 $@ unless caller(); ``` Does your module pass the 'empty subclass' test? If you say `"@SUBCLASS::ISA = qw(YOURCLASS);"` your applications should be able to use SUBCLASS in exactly the same way as YOURCLASS. For example, does your application still work if you change: `"$obj = YOURCLASS->new();"` into: `"$obj = SUBCLASS->new();"` ? Avoid keeping any state information in your packages. It makes it difficult for multiple other packages to use yours. Keep state information in objects. Always use **-w**. Try to `"use strict;"` (or `"use strict qw(...);"`). Remember that you can add `"no strict qw(...);"` to individual blocks of code that need less strictness. Always use **-w**. Follow the guidelines in perlstyle. Always use **-w**. - • Some simple style guidelines The perlstyle manual supplied with Perl has many helpful points. Coding style is a matter of personal taste. Many people evolve their style over several years as they learn what helps them write and maintain good code. Here's one set of assorted suggestions that seem to be widely used by experienced developers: Use underscores to separate words. It is generally easier to read `$var_names_like_this` than `$VarNamesLikeThis`, especially for non-native speakers of English. It's also a simple rule that works consistently with VAR\_NAMES\_LIKE\_THIS. Package/Module names are an exception to this rule. Perl informally reserves lowercase module names for 'pragma' modules like integer and strict. Other modules normally begin with a capital letter and use mixed case with no underscores (need to be short and portable). You may find it helpful to use letter case to indicate the scope or nature of a variable. For example: ``` $ALL_CAPS_HERE constants only (beware clashes with Perl vars) $Some_Caps_Here package-wide global/static $no_caps_here function scope my() or local() variables ``` Function and method names seem to work best as all lowercase. e.g., `"$obj->as_string()"`. You can use a leading underscore to indicate that a variable or function should not be used outside the package that defined it. - • Select what to export. Do NOT export method names! Do NOT export anything else by default without a good reason! Exports pollute the namespace of the module user. If you must export try to use `@EXPORT_OK` in preference to `@EXPORT` and avoid short or common names to reduce the risk of name clashes. Generally anything not exported is still accessible from outside the module using the ModuleName::item\_name (or `"$blessed_ref->method"`) syntax. By convention you can use a leading underscore on names to indicate informally that they are 'internal' and not for public use. (It is actually possible to get private functions by saying: `"my $subref = sub { ... }; &$subref;"`. But there's no way to call that directly as a method, because a method must have a name in the symbol table.) As a general rule, if the module is trying to be object oriented then export nothing. If it's just a collection of functions then `@EXPORT_OK` anything but use `@EXPORT` with caution. - • Select a name for the module. This name should be as descriptive, accurate, and complete as possible. Avoid any risk of ambiguity. Always try to use two or more whole words. Generally the name should reflect what is special about what the module does rather than how it does it. Please use nested module names to group informally or categorize a module. There should be a very good reason for a module not to have a nested name. Module names should begin with a capital letter. Having 57 modules all called Sort will not make life easy for anyone (though having 23 called Sort::Quick is only marginally better :-). Imagine someone trying to install your module alongside many others. If you are developing a suite of related modules/classes it's good practice to use nested classes with a common prefix as this will avoid namespace clashes. For example: Xyz::Control, Xyz::View, Xyz::Model etc. Use the modules in this list as a naming guide. If adding a new module to a set, follow the original author's standards for naming modules and the interface to methods in those modules. If developing modules for private internal or project specific use, that will never be released to the public, then you should ensure that their names will not clash with any future public module. You can do this either by using the reserved Local::\* category or by using a category name that includes an underscore like Foo\_Corp::\*. To be portable each component of a module name should be limited to 11 characters. If it might be used on MS-DOS then try to ensure each is unique in the first 8 characters. Nested modules make this easier. For additional guidance on the naming of modules, please consult: ``` https://pause.perl.org/pause/query?ACTION=pause_namingmodules ``` or send mail to the \ mailing list. - • Have you got it right? How do you know that you've made the right decisions? Have you picked an interface design that will cause problems later? Have you picked the most appropriate name? Do you have any questions? The best way to know for sure, and pick up many helpful suggestions, is to ask someone who knows. The \ mailing list is useful for this purpose; it's also accessible via news interface as perl.module-authors at nntp.perl.org. All you need to do is post a short summary of the module, its purpose and interfaces. A few lines on each of the main methods is probably enough. (If you post the whole module it might be ignored by busy people - generally the very people you want to read it!) Don't worry about posting if you can't say when the module will be ready - just say so in the message. It might be worth inviting others to help you, they may be able to complete it for you! - • README and other Additional Files. It's well known that software developers usually fully document the software they write. If, however, the world is in urgent need of your software and there is not enough time to write the full documentation please at least provide a README file containing: - • A description of the module/package/extension etc. - • A copyright notice - see below. - • Prerequisites - what else you may need to have. - • How to build it - possible changes to Makefile.PL etc. - • How to install it. - • Recent changes in this release, especially incompatibilities - • Changes / enhancements you plan to make in the future. If the README file seems to be getting too large you may wish to split out some of the sections into separate files: INSTALL, Copying, ToDo etc. - • Adding a Copyright Notice. How you choose to license your work is a personal decision. The general mechanism is to assert your Copyright and then make a declaration of how others may copy/use/modify your work. Perl, for example, is supplied with two types of licence: The GNU GPL and The Artistic Licence (see the files README, Copying, and Artistic, or perlgpl and perlartistic). Larry has good reasons for NOT just using the GNU GPL. My personal recommendation, out of respect for Larry, Perl, and the Perl community at large is to state something simply like: ``` Copyright (c) 1995 Your Name. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. ``` This statement should at least appear in the README file. You may also wish to include it in a Copying file and your source files. Remember to include the other words in addition to the Copyright. - • Give the module a version/issue/release number. To be fully compatible with the Exporter and MakeMaker modules you should store your module's version number in a non-my package variable called `$VERSION`. This should be a positive floating point number with at least two digits after the decimal (i.e., hundredths, e.g, `"$VERSION = "0.01""`). Don't use a "1.3.2" style version. 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. If possible, register the module with CPAN. Follow the instructions and links on: ``` https://www.cpan.org/modules/04pause.html ``` and upload to: ``` https://pause.perl.org/ ``` and notify \. This will allow anyone to install your module using the `"cpan"` tool distributed with Perl. By using the WWW interface you can ask the Upload Server to mirror your modules from your ftp or WWW site into your own directory on CPAN! - • Take care when changing a released module. Always strive to remain compatible with previous released versions. Otherwise try to add a mechanism to revert to the old behavior if people rely on it. Document incompatible changes. ### Guidelines for Converting Perl 4 Library Scripts into Modules - • There is no requirement to convert anything. If it ain't broke, don't fix it! Perl 4 library scripts should continue to work with no problems. You may need to make some minor changes (like escaping non-array @'s in double quoted strings) but there is no need to convert a .pl file into a Module for just that. - • Consider the implications. All Perl applications that make use of the script will need to be changed (slightly) if the script is converted into a module. Is it worth it unless you plan to make other changes at the same time? - • Make the most of the opportunity. If you are going to convert the script to a module you can use the opportunity to redesign the interface. The guidelines for module creation above include many of the issues you should consider. - • The pl2pm utility will get you started. This utility will read \*.pl files (given as parameters) and write corresponding \*.pm files. The pl2pm utilities does the following: - • Adds the standard Module prologue lines - • Converts package specifiers from ' to :: - • Converts die(...) to croak(...) - • Several other minor changes Being a mechanical process pl2pm is not bullet proof. The converted code will need careful checking, especially any package statements. Don't delete the original .pl file till the new .pm one works! ### Guidelines for Reusing Application Code - • Complete applications rarely belong in the Perl Module Library. - • Many applications contain some Perl code that could be reused. Help save the world! Share your code in a form that makes it easy to reuse. - • Break-out the reusable code into one or more separate module files. - • Take the opportunity to reconsider and redesign the interfaces. - • In some cases the 'application' can then be reduced to a small fragment of code built on top of the reusable modules. In these cases the application could invoked as: ``` % perl -e 'use Module::Name; method(@ARGV)' ... or % perl -mModule::Name ... (in perl5.002 or higher) ``` ## NOTE Perl does not enforce private and public parts of its modules as you may have been used to in other languages like C++, Ada, or Modula-17. Perl doesn't have an infatuation with enforced privacy. It would prefer that you stayed out of its living room because you weren't invited, not because it has a shotgun. The module and its user have a contract, part of which is common law, and part of which is "written". Part of the common law contract is that a module doesn't pollute any namespace it wasn't asked to. The written contract for the module (A.K.A. documentation) may make other provisions. But then you know when you `"use RedefineTheWorld"` that you're redefining the world and willing to take the consequences.