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- NAME
- perlmodlib - constructing new Perl modules and finding existing
- ones
-
- DESCRIPTION
- THE PERL MODULE LIBRARY
- A number of modules are included the Perl distribution. These
- are described below, and all end in .pm. 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 module.) 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 pragmas 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 any of these
- by saying:
-
- no integer;
- no strict 'refs';
-
-
- which lasts until the end of that BLOCK.
-
- Unlike the pragmas that effect the `$^H' hints variable, the
- `use vars' and `use subs' declarations are not BLOCK-scoped.
- They 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).
-
- use autouse MODULE => qw(sub1 sub2 sub3)
- Defers `require MODULE' until someone calls one of
- the specified subroutines (which must be exported by
- MODULE). This pragma should be used with caution,
- and only when necessary.
-
- blib manipulate @INC at compile time to use MakeMaker's
- uninstalled version of a package
-
- diagnostics force verbose warning diagnostics
-
- integer compute arithmetic in integer instead of double
-
- less request less of something from the compiler
-
- lib manipulate @INC at compile time
-
- locale use or ignore current locale for builtin operations (see
- the perllocale manpage)
-
- ops restrict named opcodes when compiling or running Perl
- code
-
- overload overload basic Perl operations
-
- re alter behaviour of regular expressions
-
- sigtrap enable simple signal handling
-
- strict restrict unsafe constructs
-
- subs predeclare sub names
-
- vmsish adopt certain VMS-specific behaviors
-
- vars predeclare global variable names
-
-
- 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.
-
- AnyDBM_File provide framework for multiple DBMs
-
- AutoLoader load functions only on demand
-
- AutoSplit split a package for autoloading
-
- Benchmark benchmark running times of code
-
- CPAN interface to Comprehensive Perl Archive Network
-
- CPAN::FirstTime
- create a CPAN configuration file
-
- CPAN::Nox run CPAN while avoiding compiled extensions
-
- Carp warn of errors (from perspective of caller)
-
- Class::Struct
- declare struct-like datatypes
-
- Config access Perl configuration information
-
- Cwd get pathname of current working directory
-
- DB_File access to Berkeley DB
-
- Devel::SelfStubber
- generate stubs for a SelfLoading module
-
- DirHandle supply object methods for directory handles
-
- DynaLoader dynamically load C libraries into Perl code
-
- English use nice English (or awk) names for ugly punctuation
- variables
-
- Env import environment variables
-
- Exporter implements default import method for modules
-
- ExtUtils::Embed
- utilities for embedding Perl in C/C++ applications
-
- ExtUtils::Install
- install files from here to there
-
- ExtUtils::Liblist
- determine libraries to use and how to use them
-
- ExtUtils::MM_OS2
- methods to override Unix behaviour in
- ExtUtils::MakeMaker
-
- ExtUtils::MM_Unix
- methods used by ExtUtils::MakeMaker
-
- ExtUtils::MM_VMS
- methods to override Unix behaviour in
- ExtUtils::MakeMaker
-
- ExtUtils::MakeMaker
- create an extension Makefile
-
- 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::testlib
- add blib/* directories to @INC
-
- Fatal make errors in builtins or Perl functions fatal
-
- Fcntl load the C Fcntl.h defines
-
- File::Basename
- split a pathname into pieces
-
- File::CheckTree
- run many filetest checks on a tree
-
- File::Compare
- compare files or filehandles
-
- File::Copy copy files or filehandles
-
- File::Find traverse a file tree
-
- File::Path create or remove a series of directories
-
- File::Spec portably perform operations on file names
-
- File::Spec::Functions
- function call interface to File::Spec module
-
- File::stat by-name interface to Perl's builtin stat() functions
-
- FileCache keep more files open than the system permits
-
- FileHandle supply object methods for filehandles
-
- FindBin locate directory of original Perl script
-
- GDBM_File access to the gdbm library
-
- Getopt::Long
- extended processing of command line options
-
- Getopt::Std process single-character switches with switch clustering
-
- I18N::Collate
- compare 8-bit scalar data according to the current
- locale
-
- IO load various IO modules
-
- IO::File supply object methods for filehandles
-
- IO::Handle supply object methods for I/O handles
-
- IO::Pipe supply object methods for pipes
-
- 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
-
- IPC::Open2 open a process for both reading and writing
-
- IPC::Open3 open a process for reading, writing, and error handling
-
- Math::BigFloat
- arbitrary length float math package
-
- Math::BigInt
- arbitrary size integer math package
-
- Math::Complex
- complex numbers and associated mathematical
- functions
-
- Math::Trig simple interface to parts of Math::Complex for those who
- need trigonometric functions only for real numbers
-
- NDBM_File tied access to ndbm files
-
- Net::Ping Hello, anybody home?
-
- Net::hostent
- by-name interface to Perl's builtin gethost*()
- functions
-
- Net::netent by-name interface to Perl's builtin getnet*() functions
-
- Net::protoent
- by-name interface to Perl's builtin getproto*()
- functions
-
- Net::servent
- by-name interface to Perl's builtin getserv*()
- functions
-
- Opcode disable named opcodes when compiling or running Perl
- code
-
- Pod::Text convert POD data to formatted ASCII text
-
- POSIX interface to IEEE Standard 1003.1
-
- SDBM_File tied access to sdbm files
-
- Safe compile and execute code in restricted compartments
-
- 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
-
- Symbol manipulate Perl symbols and their names
-
- Sys::Hostname
- try every conceivable way to get hostname
-
- Sys::Syslog interface to the Unix syslog(3) calls
-
- Term::Cap termcap interface
-
- Term::Complete
- word completion module
-
- Term::ReadLine
- interface to various `readline' packages
-
- Test::Harness
- run Perl standard test scripts with statistics
-
- Text::Abbrev
- create an abbreviation table from a list
-
- Text::ParseWords
- parse text into an array of tokens
-
- Text::Soundex
- implementation of the Soundex Algorithm as described
- by Knuth
-
- Text::Tabs expand and unexpand tabs per the Unix expand(1) and
- unexpand(1)
-
- Text::Wrap line wrapping to form simple paragraphs
-
- Tie::Hash base class definitions for tied hashes
-
- Tie::RefHash
- base class definitions for tied hashes with
- references as keys
-
- Tie::Scalar base class definitions for tied scalars
-
- Tie::SubstrHash
- fixed-table-size, fixed-key-length hashing
-
- Time::Local efficiently compute time from local and GMT time
-
- Time::gmtime
- by-name interface to Perl's builtin gmtime()
- function
-
- Time::localtime
- by-name interface to Perl's builtin localtime()
- function
-
- Time::tm internal object used by Time::gmtime and Time::localtime
-
- UNIVERSAL base class for ALL classes (blessed references)
-
- User::grent by-name interface to Perl's builtin getgr*() functions
-
- User::pwent by-name interface to Perl's builtin getpw*() functions
-
-
- To find out *all* the modules installed on your system,
- including those without documentation or outside the standard
- release, do this:
-
- % find `perl -e 'print "@INC"'` -name '*.pm' -print
-
-
- They should all have their own documentation installed and
- accessible via your system man(1) command. If that fails, try
- the *perldoc* program.
-
- Extension Modules
-
- Extension modules are written in C (or a mix of Perl and C) and
- may be statically linked or in general are dynamically loaded
- into Perl if and when you need them. Supported extension modules
- include the Socket, Fcntl, and POSIX modules.
-
- 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 in archie(1L), the Perl FAQ or Meta-
- FAQ, the WWW page, and even with their authors before randomly
- posting asking for their present condition and disposition.
-
- CPAN
- CPAN stands for the Comprehensive Perl Archive Network. This is
- a globally replicated collection of all known Perl materials,
- including hundreds of unbundled modules. Here are the major
- categories of modules:
-
- *
- Language Extensions and Documentation Tools
-
- *
- Development Support
-
- *
- Operating System Interfaces
-
- *
- Networking, Device Control (modems) and InterProcess Communication
-
- *
- Data Types and Data Type Utilities
-
- *
- Database Interfaces
-
- *
- User Interfaces
-
- *
- Interfaces to / Emulations of Other Programming Languages
-
- *
- File Names, File Systems and File Locking (see also File Handles)
-
- *
- String Processing, Language Text Processing, Parsing, and Searching
-
- *
- Option, Argument, Parameter, and Configuration File Processing
-
- *
- Internationalization and Locale
-
- *
- Authentication, Security, and Encryption
-
- *
- World Wide Web, HTML, HTTP, CGI, MIME
-
- *
- Server and Daemon Utilities
-
- *
- Archiving and Compression
-
- *
- Images, Pixmap and Bitmap Manipulation, Drawing, and Graphing
-
- *
- Mail and Usenet News
-
- *
- Control Flow Utilities (callbacks and exceptions etc)
-
- *
- File Handle and Input/Output Stream Utilities
-
- *
- Miscellaneous Modules
-
-
- The registered CPAN sites as of this writing include the
- following. You should try to choose one close to you:
-
- *
- Africa
-
- South Africa ftp://ftp.is.co.za/programming/perl/CPAN/
- ftp://ftpza.co.za/pub/mirrors/cpan/
-
-
- *
- Asia
-
- Armenia ftp://sunsite.aua.am/pub/CPAN/
- China ftp://freesoft.cei.gov.cn/pub/languages/perl/CPAN/
- Hong Kong ftp://ftp.hkstar.com/pub/CPAN/
- Israel ftp://bioinfo.weizmann.ac.il/pub/software/perl/CPAN/
- Japan ftp://ftp.dti.ad.jp/pub/lang/CPAN/
- ftp://ftp.jaist.ac.jp/pub/lang/perl/CPAN/
- ftp://ftp.lab.kdd.co.jp/lang/perl/CPAN/
- ftp://ftp.meisei-u.ac.jp/pub/CPAN/
- ftp://mirror.nucba.ac.jp/mirror/Perl/
- Singapore ftp://ftp.nus.edu.sg/pub/unix/perl/CPAN/
- South Korea ftp://ftp.bora.net/pub/CPAN/
- ftp://ftp.nuri.net/pub/CPAN/
- Taiwan ftp://ftp.wownet.net/pub2/PERL/
- ftp://ftp1.sinica.edu.tw/pub1/perl/CPAN/
- Thailand ftp://ftp.cs.riubon.ac.th/pub/mirrors/CPAN/
- ftp://ftp.nectec.or.th/pub/mirrors/CPAN/
-
-
- *
- Australasia
-
- Australia ftp://cpan.topend.com.au/pub/CPAN/
- ftp://ftp.labyrinth.net.au/pub/perl/CPAN/
- ftp://ftp.sage-au.org.au/pub/compilers/perl/CPAN/
- ftp://mirror.aarnet.edu.au/pub/perl/CPAN/
- New Zealand ftp://ftp.auckland.ac.nz/pub/perl/CPAN/
- ftp://sunsite.net.nz/pub/languages/perl/CPAN/
-
-
- *
- Central America
-
- Costa Rica ftp://ftp.ucr.ac.cr/pub/Unix/CPAN/
-
-
- *
- Europe
-
- Austria ftp://ftp.tuwien.ac.at/pub/languages/perl/CPAN/
- Belgium ftp://ftp.kulnet.kuleuven.ac.be/pub/mirror/CPAN/
- Bulgaria ftp://ftp.ntrl.net/pub/mirrors/CPAN/
- Croatia ftp://ftp.linux.hr/pub/CPAN/
- Czech Republic ftp://ftp.fi.muni.cz/pub/perl/
- ftp://sunsite.mff.cuni.cz/Languages/Perl/CPAN/
- Denmark ftp://sunsite.auc.dk/pub/languages/perl/CPAN/
- Estonia ftp://ftp.ut.ee/pub/languages/perl/CPAN/
- Finland ftp://ftp.funet.fi/pub/languages/perl/CPAN/
- France ftp://ftp.lip6.fr/pub/perl/CPAN/
- ftp://ftp.oleane.net/pub/mirrors/CPAN/
- ftp://ftp.pasteur.fr/pub/computing/CPAN/
- Germany ftp://ftp.archive.de.uu.net/pub/CPAN/
- ftp://ftp.gmd.de/packages/CPAN/
- ftp://ftp.gwdg.de/pub/languages/perl/CPAN/
- ftp://ftp.leo.org/pub/comp/programming/languages/script/perl/CPAN/
- ftp://ftp.mpi-sb.mpg.de/pub/perl/CPAN/
- ftp://ftp.rz.ruhr-uni-bochum.de/pub/CPAN/
- ftp://ftp.uni-erlangen.de/pub/source/CPAN/
- ftp://ftp.uni-hamburg.de/pub/soft/lang/perl/CPAN/
- Greece ftp://ftp.ntua.gr/pub/lang/perl/
- Hungary ftp://ftp.kfki.hu/pub/packages/perl/CPAN/
- Ireland ftp://sunsite.compapp.dcu.ie/pub/perl/
- Italy ftp://cis.uniRoma2.it/CPAN/
- ftp://ftp.flashnet.it/pub/CPAN/
- ftp://ftp.unipi.it/pub/mirror/perl/CPAN/
- Netherlands ftp://ftp.cs.uu.nl/mirror/CPAN/
- ftp://ftp.nluug.nl/pub/languages/perl/CPAN/
- Norway ftp://ftp.uit.no/pub/languages/perl/cpan/
- ftp://sunsite.uio.no/pub/languages/perl/CPAN/
- Poland ftp://ftp.man.szczecin.pl/pub/perl/CPAN/
- ftp://ftp.man.torun.pl/pub/doc/CPAN/
- ftp://ftp.pk.edu.pl/pub/lang/perl/CPAN/
- ftp://sunsite.icm.edu.pl/pub/CPAN/
- Portugal ftp://ftp.ci.uminho.pt/pub/mirrors/cpan/
- ftp://ftp.ua.pt/pub/CPAN/
- Romania ftp://ftp.dntis.ro/pub/mirrors/perl-cpan/
- ftp://ftp.dnttm.ro/pub/CPAN/
- Russia ftp://cpan.npi.msu.su/CPAN/
- ftp://ftp.sai.msu.su/pub/lang/perl/CPAN/
- Slovakia ftp://ftp.entry.sk/pub/languages/perl/CPAN/
- Slovenia ftp://ftp.arnes.si/software/perl/CPAN/
- Spain ftp://ftp.etse.urv.es/pub/perl/
- ftp://ftp.rediris.es/mirror/CPAN/
- Sweden ftp://ftp.sunet.se/pub/lang/perl/CPAN/
- Switzerland ftp://sunsite.cnlab-switch.ch/mirror/CPAN/
- Turkey ftp://sunsite.bilkent.edu.tr/pub/languages/CPAN/
- United Kingdom ftp://ftp.demon.co.uk/pub/mirrors/perl/CPAN/
- ftp://ftp.flirble.org/pub/languages/perl/CPAN/
- ftp://ftp.plig.org/pub/CPAN/
- ftp://sunsite.doc.ic.ac.uk/packages/CPAN/
- ftp://unix.hensa.ac.uk/mirrors/perl-CPAN/
-
-
- *
- North America
-
- Alberta ftp://sunsite.ualberta.ca/pub/Mirror/CPAN/
- California ftp://ftp.cdrom.com/pub/perl/CPAN/
- ftp://ftp.digital.com/pub/plan/perl/CPAN/
- Colorado ftp://ftp.cs.colorado.edu/pub/perl/CPAN/
- Florida ftp://ftp.cise.ufl.edu/pub/perl/CPAN/
- Illinois ftp://uiarchive.uiuc.edu/pub/lang/perl/CPAN/
- Indiana ftp://csociety-ftp.ecn.purdue.edu/pub/CPAN/
- ftp://ftp.uwsg.indiana.edu/pub/perl/CPAN/
- Manitoba ftp://theory.uwinnipeg.ca/pub/CPAN/
- Massachusetts ftp://ftp.ccs.neu.edu/net/mirrors/ftp.funet.fi/pub/languages/perl/CPAN/
- ftp://ftp.iguide.com/pub/mirrors/packages/perl/CPAN/
- Mexico D.F. ftp://ftp.msg.com.mx/pub/CPAN/
- New York ftp://ftp.rge.com/pub/languages/perl/
- North Carolina ftp://ftp.duke.edu/pub/perl/
- Oklahoma ftp://ftp.ou.edu/mirrors/CPAN/
- Ontario ftp://ftp.crc.ca/pub/packages/perl/CPAN/
- Oregon ftp://ftp.orst.edu/pub/packages/CPAN/
- Pennsylvania ftp://ftp.epix.net/pub/languages/perl/
- Texas ftp://ftp.sedl.org/pub/mirrors/CPAN/
- Utah ftp://mirror.xmission.com/CPAN/
- Virginia ftp://ftp.perl.org/pub/perl/CPAN/
- ftp://ruff.cs.jmu.edu/pub/CPAN/
- Washington ftp://ftp.spu.edu/pub/CPAN/
-
-
- *
- South America
-
- Brazil ftp://cpan.if.usp.br/pub/mirror/CPAN/
- Chile ftp://ftp.ing.puc.cl/pub/unix/perl/CPAN/
- ftp://sunsite.dcc.uchile.cl/pub/Lang/perl/CPAN/
-
-
- For an up-to-date listing of CPAN sites, see
- http://www.perl.com/perl/CPAN or ftp://ftp.perl.com/perl/.
-
- 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
- the perlsub manpage, the perltoot manpage, and the AutoLoader
- manpage 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.
- Use blessed references. Use the two argument form of bless
- to bless into the class name given as the first parameter of
- the constructor, e.g.,:
-
- sub new {
- my $class = shift;
- return bless {}, $class;
- }
-
-
- or even this if you'd like it to be used as either a static
- or a virtual method.
-
- sub new {
- my $self = shift;
- my $class = ref($self) || $self;
- return bless {}, $class;
- }
-
-
- Pass arrays as references so more parameters can be added
- later (it's also faster). Convert functions into methods
- where appropriate. Split large methods into smaller more
- flexible ones. Inherit methods from other modules if
- appropriate.
-
- Avoid class name tests like: `die "Invalid" unless ref $ref
- eq 'FOO''. Generally you can delete the "`eq 'FOO''" part
- with no harm at all. Let the objects look after themselves!
- Generally, avoid hard-wired class names as far as possible.
-
- Avoid `$r->Class::func()' where using `@ISA=qw(... Class
- ...)' and `$r->func()' would work (see the perlbot manpage
- for more details).
-
- Use autosplit so little used or newly added functions won't
- be a burden to programs that don't use them. Add test
- functions to the module after __END__ either using AutoSplit
- or by saying:
-
- eval join('',<main::DATA>) || die $@ unless caller();
-
-
- Does your module pass the 'empty subclass' test? If you say
- "`@SUBCLASS::ISA = qw(YOURCLASS);'" your applications should
- be able to use SUBCLASS in exactly the same way as
- YOURCLASS. For example, does your application still work if
- you change: `$obj = new YOURCLASS;' into: `$obj = new
- SUBCLASS;' ?
-
- Avoid keeping any state information in your packages. It
- makes it difficult for multiple other packages to use yours.
- Keep state information in objects.
-
- Always use -w. Try to `use strict;' (or `use strict
- qw(...);'). Remember that you can add `no strict qw(...);'
- to individual blocks of code that need less strictness.
- Always use -w. Always use -w! Follow the guidelines in the
- perlstyle(1) manual.
-
- Some simple style guidelines
- The perlstyle manual supplied with Perl has many helpful
- points.
-
- Coding style is a matter of personal taste. Many people
- evolve their style over several years as they learn what
- helps them write and maintain good code. Here's one set of
- assorted suggestions that seem to be widely used by
- experienced developers:
-
- Use underscores to separate words. It is generally easier to
- read $var_names_like_this than $VarNamesLikeThis, especially
- for non-native speakers of English. It's also a simple rule
- that works consistently with VAR_NAMES_LIKE_THIS.
-
- Package/Module names are an exception to this rule. Perl
- informally reserves lowercase module names for 'pragma'
- modules like integer and strict. Other modules normally
- begin with a capital letter and use mixed case with no
- underscores (need to be short and portable).
-
- You may find it helpful to use letter case to indicate the
- scope or nature of a variable. For example:
-
- $ALL_CAPS_HERE constants only (beware clashes with Perl vars)
- $Some_Caps_Here package-wide global/static
- $no_caps_here function scope my() or local() variables
-
-
- Function and method names seem to work best as all
- lowercase. e.g., `$obj->as_string()'.
-
- You can use a leading underscore to indicate that a variable
- or function should not be used outside the package that
- defined it.
-
- Select what to export.
- Do NOT export method names!
-
- Do NOT export anything else by default without a good
- reason!
-
- Exports pollute the namespace of the module user. If you
- must export try to use @EXPORT_OK in preference to @EXPORT
- and avoid short or common names to reduce the risk of name
- clashes.
-
- Generally anything not exported is still accessible from
- outside the module using the ModuleName::item_name (or
- `$blessed_ref->method') syntax. By convention you can use a
- leading underscore on names to indicate informally that they
- are 'internal' and not for public use.
-
- (It is actually possible to get private functions by saying:
- `my $subref = sub { ... }; &$subref;'. But there's no way to
- call that directly as a method, because a method must have a
- name in the symbol table.)
-
- As a general rule, if the module is trying to be object
- oriented then export nothing. If it's just a collection of
- functions then @EXPORT_OK anything but use @EXPORT with
- caution.
-
- Select a name for the module.
- This name should be as descriptive, accurate, and complete
- as possible. Avoid any risk of ambiguity. Always try to use
- two or more whole words. Generally the name should reflect
- what is special about what the module does rather than how
- it does it. Please use nested module names to group
- informally or categorize a module. There should be a very
- good reason for a module not to have a nested name. Module
- names should begin with a capital letter.
-
- Having 57 modules all called Sort will not make life easy
- for anyone (though having 23 called Sort::Quick is only
- marginally better :-). Imagine someone trying to install
- your module alongside many others. If in any doubt ask for
- suggestions in comp.lang.perl.misc.
-
- If you are developing a suite of related modules/classes
- it's good practice to use nested classes with a common
- prefix as this will avoid namespace clashes. For example:
- Xyz::Control, Xyz::View, Xyz::Model etc. Use the modules in
- this list as a naming guide.
-
- If adding a new module to a set, follow the original
- author's standards for naming modules and the interface to
- methods in those modules.
-
- To be portable each component of a module name should be
- limited to 11 characters. If it might be used on MS-DOS then
- try to ensure each is unique in the first 8 characters.
- Nested modules make this easier.
-
- Have you got it right?
- How do you know that you've made the right decisions? Have
- you picked an interface design that will cause problems
- later? Have you picked the most appropriate name? Do you
- have any questions?
-
- The best way to know for sure, and pick up many helpful
- suggestions, is to ask someone who knows.
- Comp.lang.perl.misc is read by just about all the people who
- develop modules and it's the best place to ask.
-
- All you need to do is post a short summary of the module,
- its purpose and interfaces. A few lines on each of the main
- methods is probably enough. (If you post the whole module it
- might be ignored by busy people - generally the very people
- you want to read it!)
-
- Don't worry about posting if you can't say when the module
- will be ready - just say so in the message. It might be
- worth inviting others to help you, they may be able to
- complete it for you!
-
- README and other Additional Files.
- It's well known that software developers usually fully
- document the software they write. If, however, the world is
- in urgent need of your software and there is not enough time
- to write the full documentation please at least provide a
- README file containing:
-
- *
- A description of the module/package/extension etc.
-
- *
- A copyright notice - see below.
-
- *
- Prerequisites - what else you may need to have.
-
- *
- How to build it - possible changes to Makefile.PL etc.
-
- *
- How to install it.
-
- *
- Recent changes in this release, especially incompatibilities
-
- *
- Changes / enhancements you plan to make in the future.
-
-
- If the README file seems to be getting too large you may
- wish to split out some of the sections into separate files:
- INSTALL, Copying, ToDo etc.
-
- Adding a Copyright Notice.
- How you choose to license your work is a personal
- decision. The general mechanism is to assert your
- Copyright and then make a declaration of how others may
- copy/use/modify your work.
-
- Perl, for example, is supplied with two types of
- licence: The GNU GPL and The Artistic Licence (see the
- files README, Copying, and Artistic). Larry has good
- reasons for NOT just using the GNU GPL.
-
- My personal recommendation, out of respect for Larry,
- Perl, and the Perl community at large is to state
- something simply like:
-
- Copyright (c) 1995 Your Name. All rights reserved.
- This program is free software; you can redistribute it and/or
- modify it under the same terms as Perl itself.
-
-
- This statement should at least appear in the README
- file. You may also wish to include it in a Copying file
- and your source files. Remember to include the other
- words in addition to the Copyright.
-
- Give the module a version/issue/release number.
- To be fully compatible with the Exporter and MakeMaker
- modules you should store your module's version number in
- a non-my package variable called $VERSION. This should
- be a floating point number with at least two digits
- after the decimal (i.e., hundredths, e.g, `$VERSION =
- "0.01"'). Don't use a "1.3.2" style version. See
- Exporter.pm in Perl5.001m or later for details.
-
- It may be handy to add a function or method to retrieve
- the number. Use the number in announcements and archive
- file names when releasing the module (ModuleName-
- 1.02.tar.Z). See perldoc ExtUtils::MakeMaker.pm for
- details.
-
- How to release and distribute a module.
- It's good idea to post an announcement of the
- availability of your module (or the module itself if
- small) to the comp.lang.perl.announce Usenet newsgroup.
- This will at least ensure very wide once-off
- distribution.
-
- If possible you should place the module into a major ftp
- archive and include details of its location in your
- announcement.
-
- Some notes about ftp archives: Please use a long
- descriptive file name that includes the version number.
- Most incoming directories will not be readable/listable,
- i.e., you won't be able to see your file after uploading
- it. Remember to send your email notification message as
- soon as possible after uploading else your file may get
- deleted automatically. Allow time for the file to be
- processed and/or check the file has been processed
- before announcing its location.
-
- FTP Archives for Perl Modules:
-
- Follow the instructions and links on
-
- http://franz.ww.tu-berlin.de/modulelist
-
-
- or upload to one of these sites:
-
- ftp://franz.ww.tu-berlin.de/incoming
- ftp://ftp.cis.ufl.edu/incoming
-
-
- and notify <upload@franz.ww.tu-berlin.de>.
-
- By using the WWW interface you can ask the Upload Server
- to mirror your modules from your ftp or WWW site into
- your own directory on CPAN!
-
- Please remember to send me an updated entry for the
- Module list!
-
- Take care when changing a released module.
- Always strive to remain compatible with previous
- released versions. Otherwise try to add a mechanism to
- revert to the old behaviour 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.
-
-