PERLMODLIB(1) PERLMODLIB(1)
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 locally 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
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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
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
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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
Fcntl load the C Fcntl.h defines
File::Basename
split a pathname into pieces
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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::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
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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
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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)
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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)
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⊕ 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/
⊕ Asia
Hong Kong ftp://ftp.hkstar.com/pub/CPAN/
Japan ftp://ftp.jaist.ac.jp/pub/lang/perl/CPAN/
ftp://ftp.lab.kdd.co.jp/lang/perl/CPAN/
South Korea ftp://ftp.nuri.net/pub/CPAN/
Taiwan ftp://dongpo.math.ncu.edu.tw/perl/CPAN/
ftp://ftp.wownet.net/pub2/PERL/
⊕ Australasia
Australia ftp://ftp.netinfo.com.au/pub/perl/CPAN/
New Zealand ftp://ftp.tekotago.ac.nz/pub/perl/CPAN/
⊕ Europe
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Austria ftp://ftp.tuwien.ac.at/pub/languages/perl/CPAN/
Belgium ftp://ftp.kulnet.kuleuven.ac.be/pub/mirror/CPAN/
Czech Republic ftp://sunsite.mff.cuni.cz/Languages/Perl/CPAN/
Denmark ftp://sunsite.auc.dk/pub/languages/perl/CPAN/
Finland ftp://ftp.funet.fi/pub/languages/perl/CPAN/
France ftp://ftp.ibp.fr/pub/perl/CPAN/
ftp://ftp.pasteur.fr/pub/computing/unix/perl/CPAN/
Germany ftp://ftp.gmd.de/packages/CPAN/
ftp://ftp.leo.org/pub/comp/programming/languages/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/Perl/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/
Italy ftp://cis.utovrm.it/CPAN/
the Netherlands ftp://ftp.cs.ruu.nl/pub/PERL/CPAN/
ftp://ftp.EU.net/packages/cpan/
Norway ftp://ftp.uit.no/pub/languages/perl/cpan/
Poland ftp://ftp.pk.edu.pl/pub/lang/perl/CPAN/
ftp://sunsite.icm.edu.pl/pub/CPAN/
Portugal ftp://ftp.ci.uminho.pt/pub/lang/perl/
ftp://ftp.telepac.pt/pub/CPAN/
Russia ftp://ftp.sai.msu.su/pub/lang/perl/CPAN/
Slovenia ftp://ftp.arnes.si/software/perl/CPAN/
Spain ftp://ftp.etse.urv.es/pub/mirror/perl/
ftp://ftp.rediris.es/mirror/CPAN/
Sweden ftp://ftp.sunet.se/pub/lang/perl/CPAN/
UK ftp://ftp.demon.co.uk/pub/mirrors/perl/CPAN/
ftp://sunsite.doc.ic.ac.uk/packages/CPAN/
ftp://unix.hensa.ac.uk/mirrors/perl-CPAN/
⊕ North America
Ontario ftp://ftp.utilis.com/public/CPAN/
ftp://enterprise.ic.gc.ca/pub/perl/CPAN/
Manitoba ftp://theory.uwinnipeg.ca/pub/CPAN/
California ftp://ftp.digital.com/pub/plan/perl/CPAN/
ftp://ftp.cdrom.com/pub/perl/CPAN/
Colorado ftp://ftp.cs.colorado.edu/pub/perl/CPAN/
Florida ftp://ftp.cis.ufl.edu/pub/perl/CPAN/
Illinois ftp://uiarchive.uiuc.edu/pub/lang/perl/CPAN/
Massachusetts ftp://ftp.iguide.com/pub/mirrors/packages/perl/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/
Oregon http://www.perl.org/CPAN/
ftp://ftp.orst.edu/pub/packages/CPAN/
Pennsylvania ftp://ftp.epix.net/pub/languages/perl/
Texas ftp://ftp.sedl.org/pub/mirrors/CPAN/
ftp://ftp.metronet.com/pub/perl/
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⊕ South America
Chile 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.,:
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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 which 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
which 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
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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.
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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:
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⊕ 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.
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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 which 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 (see 2.2 above) 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.
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Consider the implications.
All the perl applications which 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 which 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
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you stayed out of its living room because you weren't invited, not
because it has a shotgun.
The module and its user have a contract, part of which is common law, and
part of which is "written". Part of the common law contract is that a
module doesn't pollute any namespace it wasn't asked to. The written
contract for the module (A.K.A. documentation) may make other provisions.
But then you know when you use RedefineTheWorld that you're redefining
the world and willing to take the consequences.
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