Enclose the new symbols in START_EXTERN_C and END_EXTERN_C
[p5sagit/p5-mst-13.2.git] / pod / perlmodlib.pod
CommitLineData
4e860d0a 1# Generated by perlmodlib.PL DO NOT EDIT!
2
f102b883 3=head1 NAME
4
5perlmodlib - constructing new Perl modules and finding existing ones
6
7=head1 DESCRIPTION
8
9=head1 THE PERL MODULE LIBRARY
10
19799a22 11Many modules are included the Perl distribution. These are described
12below, and all end in F<.pm>. You may discover compiled library
13file (usually ending in F<.so>) or small pieces of modules to be
14autoloaded (ending in F<.al>); these were automatically generated
15by the installation process. You may also discover files in the
16library directory that end in either F<.pl> or F<.ph>. These are
17old libraries supplied so that old programs that use them still
18run. The F<.pl> files will all eventually be converted into standard
19modules, and the F<.ph> files made by B<h2ph> will probably end up
20as extension modules made by B<h2xs>. (Some F<.ph> values may
21already be available through the POSIX, Errno, or Fcntl modules.)
22The B<pl2pm> file in the distribution may help in your conversion,
23but it's just a mechanical process and therefore far from bulletproof.
f102b883 24
25=head2 Pragmatic Modules
26
19799a22 27They work somewhat like compiler directives (pragmata) in that they
28tend to affect the compilation of your program, and thus will usually
29work well only when used within a C<use>, or C<no>. Most of these
30are lexically scoped, so an inner BLOCK may countermand them
31by saying:
f102b883 32
33 no integer;
34 no strict 'refs';
4438c4b7 35 no warnings;
f102b883 36
37which lasts until the end of that BLOCK.
38
19799a22 39Some pragmas are lexically scoped--typically those that affect the
40C<$^H> hints variable. Others affect the current package instead,
77ca0c92 41like C<use vars> and C<use subs>, which allow you to predeclare a
19799a22 42variables or subroutines within a particular I<file> rather than
43just a block. Such declarations are effective for the entire file
44for which they were declared. You cannot rescind them with C<no
45vars> or C<no subs>.
f102b883 46
47The following pragmas are defined (and have their own documentation).
48
49=over 12
50
09bef843 51=item attributes
52
9e107c59 53Get/set subroutine or variable attributes
09bef843 54
19799a22 55=item attrs
f102b883 56
9e107c59 57Set/get attributes of a subroutine (deprecated)
19799a22 58
59=item autouse
60
9e107c59 61Postpone load of modules until a function is used
19799a22 62
63=item base
64
65Establish IS-A relationship with base class at compile time
f102b883 66
67=item blib
68
19799a22 69Use MakeMaker's uninstalled version of a package
70
2e1d04bc 71=item bytes
9e107c59 72
2e1d04bc 73Force byte semantics rather than character semantics
9e107c59 74
75=item charnames
76
77Define character names for C<\N{named}> string literal escape.
78
19799a22 79=item constant
80
9e107c59 81Declare constants
f102b883 82
83=item diagnostics
84
2e1d04bc 85Perl compiler pragma to force verbose warning diagnostics
19799a22 86
87=item fields
88
2e1d04bc 89Compile-time class fields
19799a22 90
91=item filetest
92
2e1d04bc 93Control the filetest permission operators
f102b883 94
95=item integer
96
4e860d0a 97Use integer arithmetic instead of floating point
f102b883 98
99=item less
100
2e1d04bc 101Request less of something from the compiler
f102b883 102
f102b883 103=item locale
104
2e1d04bc 105Use and avoid POSIX locales for built-in operations
106
107=item open
108
109Set default disciplines for input and output
f102b883 110
111=item ops
112
9e107c59 113Restrict unsafe operations when compiling
f102b883 114
115=item overload
116
2e1d04bc 117Package for overloading perl operations
f102b883 118
b3eb6a9b 119=item re
120
2e1d04bc 121Alter regular expression behaviour
b3eb6a9b 122
f102b883 123=item sigtrap
124
9e107c59 125Enable simple signal handling
f102b883 126
127=item strict
128
9e107c59 129Restrict unsafe constructs
f102b883 130
131=item subs
132
2e1d04bc 133Predeclare sub names
f102b883 134
4e860d0a 135=item unicode::distinct
136
137Strictly distinguish UTF8 data and non-UTF data.
138
19799a22 139=item utf8
f102b883 140
1fa7ca25 141Enable/disable UTF-8 (or UTF-EBCDIC) in source code
f102b883 142
143=item vars
144
2e1d04bc 145Predeclare global variable names (obsolete)
f102b883 146
4438c4b7 147=item warnings
0453d815 148
9e107c59 149Control optional warnings
19799a22 150
13a2d996 151=item warnings::register
152
153Warnings import function
154
f102b883 155=back
156
157=head2 Standard Modules
158
159Standard, bundled modules are all expected to behave in a well-defined
160manner with respect to namespace pollution because they use the
161Exporter module. See their own documentation for details.
162
163=over 12
164
165=item AnyDBM_File
166
2e1d04bc 167Provide framework for multiple DBMs
f102b883 168
dc6b6eef 169=item Attribute::Handlers
170
171Simpler definition of attribute handlers
172
f102b883 173=item AutoLoader
174
9e107c59 175Load subroutines only on demand
f102b883 176
177=item AutoSplit
178
9e107c59 179Split a package for autoloading
f102b883 180
19799a22 181=item B
182
2e1d04bc 183The Perl Compiler
19799a22 184
185=item B::Asmdata
186
187Autogenerated data about Perl ops, used to generate bytecode
188
189=item B::Assembler
190
191Assemble Perl bytecode
192
193=item B::Bblock
194
195Walk basic blocks
196
197=item B::Bytecode
198
199Perl compiler's bytecode backend
200
201=item B::C
202
203Perl compiler's C backend
204
205=item B::CC
206
207Perl compiler's optimized C translation backend
208
4e860d0a 209=item B::Concise
210
211Walk Perl syntax tree, printing concise info about ops
212
19799a22 213=item B::Debug
214
215Walk Perl syntax tree, printing debug info about ops
216
217=item B::Deparse
218
2e1d04bc 219Perl compiler backend to produce perl code
19799a22 220
221=item B::Disassembler
222
223Disassemble Perl bytecode
224
225=item B::Lint
226
2e1d04bc 227Perl lint
19799a22 228
229=item B::Showlex
230
231Show lexical variables used in functions or files
232
233=item B::Stackobj
234
235Helper module for CC backend
236
13a2d996 237=item B::Stash
238
239Show what stashes are loaded
240
19799a22 241=item B::Terse
242
243Walk Perl syntax tree, printing terse info about ops
244
245=item B::Xref
246
247Generates cross reference reports for Perl programs
248
f102b883 249=item Benchmark
250
2e1d04bc 251Benchmark running times of Perl code
9e107c59 252
253=item ByteLoader
254
2e1d04bc 255Load byte compiled perl code
f102b883 256
19799a22 257=item CGI
258
2e1d04bc 259Simple Common Gateway Interface Class
19799a22 260
261=item CGI::Apache
262
2e1d04bc 263Backward compatibility module for CGI.pm
19799a22 264
265=item CGI::Carp
266
267CGI routines for writing to the HTTPD (or other) error log
268
269=item CGI::Cookie
270
271Interface to Netscape Cookies
272
273=item CGI::Fast
274
275CGI Interface for Fast CGI
276
9e107c59 277=item CGI::Pretty
278
279Module to produce nicely formatted HTML code
280
19799a22 281=item CGI::Push
282
283Simple Interface to Server Push
284
285=item CGI::Switch
286
2e1d04bc 287Backward compatibility module for defunct CGI::Switch
19799a22 288
4e860d0a 289=item CGI::Util
290
291Internal utilities used by CGI module
292
f102b883 293=item CPAN
294
2e1d04bc 295Query, download and build perl modules from CPAN sites
f102b883 296
297=item CPAN::FirstTime
298
2e1d04bc 299Utility for CPAN::Config file Initialization
f102b883 300
301=item CPAN::Nox
302
19799a22 303Wrapper around CPAN.pm without using any XS module
f102b883 304
305=item Carp
306
2e1d04bc 307Warn of errors (from perspective of caller)
9e107c59 308
4e860d0a 309=item Carp::Heavy
310
311No user serviceable parts inside
312
313=item Class::ISA
314
315Report the search path for a class's ISA tree
316
f102b883 317=item Class::Struct
318
9e107c59 319Declare struct-like datatypes as Perl classes
f102b883 320
f102b883 321=item Cwd
322
9e107c59 323Get pathname of current working directory
f102b883 324
19799a22 325=item DB
326
2e1d04bc 327Programmatic interface to the Perl debugging API (draft, subject to
19799a22 328
f102b883 329=item DB_File
330
19799a22 331Perl5 access to Berkeley DB version 1.x
332
f102b883 333=item Devel::SelfStubber
334
9e107c59 335Generate stubs for a SelfLoading module
f102b883 336
4e860d0a 337=item Digest
338
339Modules that calculate message digests
340
f102b883 341=item DirHandle
342
9e107c59 343Supply object methods for directory handles
f102b883 344
19799a22 345=item Dumpvalue
346
2e1d04bc 347Provides screen dump of Perl data.
f102b883 348
13a2d996 349=item Encode
350
351Character encodings
352
4e860d0a 353=item Encode::EncodeFormat
354
355The format of encoding tables of the Encode extension
356
357=item Encode::Tcl
358
359Tcl encodings
360
f102b883 361=item English
362
2e1d04bc 363Use nice English (or awk) names for ugly punctuation variables
f102b883 364
365=item Env
366
2e1d04bc 367Perl module that imports environment variables as scalars or arrays
f102b883 368
369=item Exporter
370
2e1d04bc 371Implements default import method for modules
9e107c59 372
373=item Exporter::Heavy
374
375Exporter guts
19799a22 376
377=item ExtUtils::Command
378
2e1d04bc 379Utilities to replace common UNIX commands in Makefiles etc.
f102b883 380
422a9aca 381=item ExtUtils::Constant
382
383Generate XS code to import C header constants
384
f102b883 385=item ExtUtils::Embed
386
2e1d04bc 387Utilities for embedding Perl in C/C++ applications
f102b883 388
389=item ExtUtils::Install
390
9e107c59 391Install files from here to there
f102b883 392
19799a22 393=item ExtUtils::Installed
394
395Inventory management of installed modules
396
f102b883 397=item ExtUtils::Liblist
398
9e107c59 399Determine libraries to use and how to use them
400
401=item ExtUtils::MM_Cygwin
402
2e1d04bc 403Methods to override UN*X behaviour in ExtUtils::MakeMaker
f102b883 404
5d80033a 405=item ExtUtils::MM_NW5
406
407Methods to override UN*X behaviour in ExtUtils::MakeMaker
408
f102b883 409=item ExtUtils::MM_OS2
410
2e1d04bc 411Methods to override UN*X behaviour in ExtUtils::MakeMaker
f102b883 412
413=item ExtUtils::MM_Unix
414
9e107c59 415Methods used by ExtUtils::MakeMaker
f102b883 416
417=item ExtUtils::MM_VMS
418
2e1d04bc 419Methods to override UN*X behaviour in ExtUtils::MakeMaker
19799a22 420
421=item ExtUtils::MM_Win32
422
2e1d04bc 423Methods to override UN*X behaviour in ExtUtils::MakeMaker
f102b883 424
425=item ExtUtils::MakeMaker
426
9e107c59 427Create an extension Makefile
f102b883 428
429=item ExtUtils::Manifest
430
9e107c59 431Utilities to write and check a MANIFEST file
f102b883 432
433=item ExtUtils::Mkbootstrap
434
9e107c59 435Make a bootstrap file for use by DynaLoader
f102b883 436
437=item ExtUtils::Mksymlists
438
9e107c59 439Write linker options files for dynamic extension
f102b883 440
19799a22 441=item ExtUtils::Packlist
442
9e107c59 443Manage .packlist files
19799a22 444
f102b883 445=item ExtUtils::testlib
446
9e107c59 447Add blib/* directories to @INC
f102b883 448
b6c543e3 449=item Fatal
450
9e107c59 451Replace functions with equivalents which succeed or die
b6c543e3 452
f102b883 453=item Fcntl
454
2e1d04bc 455Load the C Fcntl.h defines
f102b883 456
457=item File::Basename
458
9e107c59 459Split a pathname into pieces
460
461=item File::CheckTree
462
463Run many filetest checks on a tree
f102b883 464
f102b883 465=item File::Compare
466
19799a22 467Compare files or filehandles
f102b883 468
469=item File::Copy
470
19799a22 471Copy files or filehandles
472
473=item File::DosGlob
474
2e1d04bc 475DOS like globbing and then some
f102b883 476
477=item File::Find
478
2e1d04bc 479Traverse a file tree
f102b883 480
481=item File::Path
482
2e1d04bc 483Create or remove directory trees
f102b883 484
f505c983 485=item File::Spec
486
9e107c59 487Portably perform operations on file names
f505c983 488
165c0277 489=item File::Spec::Epoc
490
491Methods for Epoc file specs
492
f505c983 493=item File::Spec::Functions
494
9e107c59 495Portably perform operations on file names
19799a22 496
497=item File::Spec::Mac
498
499File::Spec for MacOS
500
501=item File::Spec::OS2
502
9e107c59 503Methods for OS/2 file specs
19799a22 504
505=item File::Spec::Unix
506
9e107c59 507Methods used by File::Spec
19799a22 508
509=item File::Spec::VMS
510
9e107c59 511Methods for VMS file specs
19799a22 512
513=item File::Spec::Win32
514
9e107c59 515Methods for Win32 file specs
f505c983 516
2e1d04bc 517=item File::Temp
518
519Return name and handle of a temporary file safely
520
f102b883 521=item File::stat
522
9e107c59 523By-name interface to Perl's built-in stat() functions
f102b883 524
525=item FileCache
526
9e107c59 527Keep more files open than the system permits
f102b883 528
529=item FileHandle
530
9e107c59 531Supply object methods for filehandles
f102b883 532
165c0277 533=item Filter::Simple
534
535Simplified source filtering
536
f102b883 537=item FindBin
538
2e1d04bc 539Locate directory of original perl script
f102b883 540
541=item Getopt::Long
542
9e107c59 543Extended processing of command line options
f102b883 544
545=item Getopt::Std
546
19799a22 547Process single-character switches with switch clustering
f102b883 548
549=item I18N::Collate
550
2e1d04bc 551Compare 8-bit scalar data according to the current locale
f102b883 552
422a9aca 553=item I18N::LangTags
554
555Functions for dealing with RFC3066-style language tags
556
557=item I18N::LangTags::List
558
4f233aa4 559Tags and names for human languages
422a9aca 560
f102b883 561=item IO
562
2e1d04bc 563Load various IO modules
f102b883 564
565=item IPC::Open2
566
9e107c59 567Open a process for both reading and writing
f102b883 568
569=item IPC::Open3
570
9e107c59 571Open a process for reading, writing, and error handling
f102b883 572
4e860d0a 573=item Locale::Constants
574
575Constants for Locale codes
576
577=item Locale::Country
578
579ISO codes for country identification (ISO 3166)
580
581=item Locale::Currency
582
583ISO three letter codes for currency identification (ISO 4217)
584
585=item Locale::Language
586
587ISO two letter codes for language identification (ISO 639)
588
422a9aca 589=item Locale::Maketext
590
591Framework for localization
592
593=item Locale::Maketext::TPJ13
594
595Article about software localization
596
f102b883 597=item Math::BigFloat
598
5d80033a 599Arbitrary size floating point math package
f102b883 600
601=item Math::BigInt
602
19799a22 603Arbitrary size integer math package
f102b883 604
605=item Math::Complex
606
9e107c59 607Complex numbers and associated mathematical functions
f102b883 608
404b15a1 609=item Math::Trig
610
9e107c59 611Trigonometric functions
f102b883 612
5d80033a 613=item Memoize
614
615Make your functions faster by trading space for time
616
617=item Memoize::AnyDBM_File
618
619Glue to provide EXISTS for AnyDBM_File for Storable use
620
621=item Memoize::Expire
622
623Plug-in module for automatic expiration of memoized values
624
625=item Memoize::ExpireFile
626
627Test for Memoize expiration semantics
628
629=item Memoize::ExpireTest
630
631Test for Memoize expiration semantics
632
633=item Memoize::NDBM_File
634
635Glue to provide EXISTS for NDBM_File for Storable use
636
637=item Memoize::SDBM_File
638
639Glue to provide EXISTS for SDBM_File for Storable use
640
641=item Memoize::Saves
642
643Plug-in module to specify which return values should be memoized
644
645=item Memoize::Storable
646
647Store Memoized data in Storable database
648
2e1d04bc 649=item NDBM_File
650
651Tied access to ndbm files
652
1fa7ca25 653=item NEXT
654
655Provide a pseudo-class NEXT that allows method redispatch
656
5d80033a 657=item Net::Cmd
658
659Network Command class (as used by FTP, SMTP etc)
660
661=item Net::Config
662
663Local configuration data for libnet
664
665=item Net::Domain
666
667Attempt to evaluate the current host's internet name and domain
668
669=item Net::DummyInetd
670
671A dummy Inetd server
672
673=item Net::FTP
674
675FTP Client class
676
677=item Net::NNTP
678
679NNTP Client class
680
681=item Net::Netrc
682
683OO interface to users netrc file
684
685=item Net::PH
686
687CCSO Nameserver Client class
688
689=item Net::POP3
690
691Post Office Protocol 3 Client class (RFC1081)
692
f102b883 693=item Net::Ping
694
9e107c59 695Check a remote host for reachability
f102b883 696
5d80033a 697=item Net::SMTP
698
699Simple Mail Transfer Protocol Client
700
701=item Net::SNPP
702
703Simple Network Pager Protocol Client
704
705=item Net::Time
706
707Time and daytime network client interface
708
f102b883 709=item Net::hostent
710
9e107c59 711By-name interface to Perl's built-in gethost*() functions
f102b883 712
5d80033a 713=item Net::libnetFAQ
714
715Libnet Frequently Asked Questions
716
f102b883 717=item Net::netent
718
9e107c59 719By-name interface to Perl's built-in getnet*() functions
f102b883 720
721=item Net::protoent
722
9e107c59 723By-name interface to Perl's built-in getproto*() functions
f102b883 724
725=item Net::servent
726
9e107c59 727By-name interface to Perl's built-in getserv*() functions
f102b883 728
19799a22 729=item O
f102b883 730
19799a22 731Generic interface to Perl Compiler backends
f102b883 732
2e1d04bc 733=item ODBM_File
f102b883 734
2e1d04bc 735Tied access to odbm files
f102b883 736
2e1d04bc 737=item Opcode
f102b883 738
2e1d04bc 739Disable named opcodes when compiling perl code
19799a22 740
4e860d0a 741=item POSIX
742
743Perl interface to IEEE Std 1003.1
744
745=item PerlIO
746
747On demand loader for PerlIO layers and root of PerlIO::* name space
748
9e107c59 749=item Pod::Checker
750
751Check pod documents for syntax errors
752
2e1d04bc 753=item Pod::Find
754
755Find POD documents in directory trees
756
19799a22 757=item Pod::Html
758
9e107c59 759Module to convert pod files to HTML
760
761=item Pod::InputObjects
762
2e1d04bc 763Objects representing POD input paragraphs, commands, etc.
9e107c59 764
13a2d996 765=item Pod::LaTeX
766
767Convert Pod data to formatted Latex
768
9e107c59 769=item Pod::Man
770
771Convert POD data to formatted *roff input
772
2e1d04bc 773=item Pod::ParseUtils
774
775Helpers for POD parsing and conversion
776
9e107c59 777=item Pod::Parser
778
779Base class for creating POD filters and translators
780
2e1d04bc 781=item Pod::Plainer
782
783Perl extension for converting Pod to old style Pod.
784
9e107c59 785=item Pod::Select
786
787Extract selected sections of POD from input
19799a22 788
789=item Pod::Text
790
9e107c59 791Convert POD data to formatted ASCII text
792
793=item Pod::Text::Color
794
795Convert POD data to formatted color ASCII text
796
4e860d0a 797=item Pod::Text::Overstrike
798
799Convert POD data to formatted overstrike text
800
2e1d04bc 801=item Pod::Text::Termcap
802
803Convert POD data to ASCII text with format escapes
804
9e107c59 805=item Pod::Usage
806
807Print a usage message from embedded pod documentation
f102b883 808
809=item SDBM_File
810
19799a22 811Tied access to sdbm files
f102b883 812
813=item Safe
814
19799a22 815Compile and execute code in restricted compartments
f102b883 816
817=item Search::Dict
818
9e107c59 819Search for key in dictionary file
f102b883 820
821=item SelectSaver
822
9e107c59 823Save and restore selected file handle
f102b883 824
825=item SelfLoader
826
9e107c59 827Load functions only on demand
f102b883 828
829=item Shell
830
2e1d04bc 831Run shell commands transparently within perl
f102b883 832
833=item Socket
834
2e1d04bc 835Load the C socket.h defines and structure manipulators
f102b883 836
13a2d996 837=item Storable
838
839Persistency for perl data structures
840
4e860d0a 841=item Switch
842
843A switch statement for Perl
844
f102b883 845=item Symbol
846
9e107c59 847Manipulate Perl symbols and their names
f102b883 848
2e1d04bc 849=item Term::ANSIColor
f102b883 850
2e1d04bc 851Color screen output using ANSI escape sequences
f102b883 852
853=item Term::Cap
854
2e1d04bc 855Perl termcap interface
f102b883 856
857=item Term::Complete
858
2e1d04bc 859Perl word completion module
f102b883 860
861=item Term::ReadLine
862
2e1d04bc 863Perl interface to various C<readline> packages. If
19799a22 864
865=item Test
866
9e107c59 867Provides a simple framework for writing test scripts
f102b883 868
869=item Test::Harness
870
2e1d04bc 871Run perl standard test scripts with statistics
f102b883 872
873=item Text::Abbrev
874
9e107c59 875Create an abbreviation table from a list
f102b883 876
4e860d0a 877=item Text::Balanced
878
879Extract delimited text sequences from strings.
880
f102b883 881=item Text::ParseWords
882
2e1d04bc 883Parse text into an array of tokens or array of arrays
f102b883 884
885=item Text::Soundex
886
2e1d04bc 887Implementation of the Soundex Algorithm as Described by Knuth
f102b883 888
4e860d0a 889=item Text::Tabs
890
891Expand and unexpand tabs per the unix expand(1) and unexpand(1)
892
f102b883 893=item Text::Wrap
894
9e107c59 895Line wrapping to form simple paragraphs
19799a22 896
897=item Tie::Array
898
9e107c59 899Base class for tied arrays
19799a22 900
901=item Tie::Handle
902
9e107c59 903Base class definitions for tied handles
19799a22 904
9e107c59 905=item Tie::Hash
f102b883 906
9e107c59 907Base class definitions for tied hashes
f102b883 908
909=item Tie::RefHash
910
9e107c59 911Use references as hash keys
f102b883 912
9e107c59 913=item Tie::Scalar
f102b883 914
9e107c59 915Base class definitions for tied scalars
f102b883 916
917=item Tie::SubstrHash
918
19799a22 919Fixed-table-size, fixed-key-length hashing
f102b883 920
921=item Time::Local
922
9e107c59 923Efficiently compute time from local and GMT time
f102b883 924
925=item Time::gmtime
926
9e107c59 927By-name interface to Perl's built-in gmtime() function
f102b883 928
929=item Time::localtime
930
9e107c59 931By-name interface to Perl's built-in localtime() function
f102b883 932
933=item Time::tm
934
9e107c59 935Internal object used by Time::gmtime and Time::localtime
f102b883 936
937=item UNIVERSAL
938
9e107c59 939Base class for ALL classes (blessed references)
f102b883 940
941=item User::grent
942
9e107c59 943By-name interface to Perl's built-in getgr*() functions
f102b883 944
945=item User::pwent
946
9e107c59 947By-name interface to Perl's built-in getpw*() functions
f102b883 948
4e860d0a 949=item Win32
950
951Interfaces to some Win32 API Functions
952
f102b883 953=back
954
19799a22 955To find out I<all> modules installed on your system, including
2e1d04bc 956those without documentation or outside the standard release,
b1866b2d 957just do this:
f102b883 958
5a964f20 959 % find `perl -e 'print "@INC"'` -name '*.pm' -print
f102b883 960
2e1d04bc 961They should all have their own documentation installed and accessible
962via your system man(1) command. If you do not have a B<find>
19799a22 963program, you can use the Perl B<find2perl> program instead, which
964generates Perl code as output you can run through perl. If you
965have a B<man> program but it doesn't find your modules, you'll have
2e1d04bc 966to fix your manpath. See L<perl> for details. If you have no
967system B<man> command, you might try the B<perldoc> program.
f102b883 968
969=head2 Extension Modules
970
19799a22 971Extension modules are written in C (or a mix of Perl and C). They
972are usually dynamically loaded into Perl if and when you need them,
2e1d04bc 973but may also be be linked in statically. Supported extension modules
19799a22 974include Socket, Fcntl, and POSIX.
f102b883 975
976Many popular C extension modules do not come bundled (at least, not
19799a22 977completely) due to their sizes, volatility, or simply lack of time
978for adequate testing and configuration across the multitude of
979platforms on which Perl was beta-tested. You are encouraged to
980look for them on CPAN (described below), or using web search engines
981like Alta Vista or Deja News.
f102b883 982
983=head1 CPAN
984
19799a22 985CPAN stands for Comprehensive Perl Archive Network; it's a globally
986replicated trove of Perl materials, including documentation, style
2e1d04bc 987guides, tricks and traps, alternate ports to non-Unix systems and
19799a22 988occasional binary distributions for these. Search engines for
989CPAN can be found at http://cpan.perl.com/ and at
990http://theory.uwinnipeg.ca/mod_perl/cpan-search.pl .
991
992Most importantly, CPAN includes around a thousand unbundled modules,
993some of which require a C compiler to build. Major categories of
994modules are:
f102b883 995
4e860d0a 996=over
f102b883 997
998=item *
551e1d92 999
f102b883 1000Language Extensions and Documentation Tools
1001
1002=item *
551e1d92 1003
f102b883 1004Development Support
1005
1006=item *
551e1d92 1007
f102b883 1008Operating System Interfaces
1009
1010=item *
551e1d92 1011
f102b883 1012Networking, Device Control (modems) and InterProcess Communication
1013
1014=item *
551e1d92 1015
f102b883 1016Data Types and Data Type Utilities
1017
1018=item *
551e1d92 1019
f102b883 1020Database Interfaces
1021
1022=item *
551e1d92 1023
f102b883 1024User Interfaces
1025
1026=item *
551e1d92 1027
f102b883 1028Interfaces to / Emulations of Other Programming Languages
1029
1030=item *
551e1d92 1031
f102b883 1032File Names, File Systems and File Locking (see also File Handles)
1033
1034=item *
551e1d92 1035
f102b883 1036String Processing, Language Text Processing, Parsing, and Searching
1037
1038=item *
551e1d92 1039
f102b883 1040Option, Argument, Parameter, and Configuration File Processing
1041
1042=item *
551e1d92 1043
f102b883 1044Internationalization and Locale
1045
1046=item *
551e1d92 1047
f102b883 1048Authentication, Security, and Encryption
1049
1050=item *
551e1d92 1051
f102b883 1052World Wide Web, HTML, HTTP, CGI, MIME
1053
1054=item *
551e1d92 1055
f102b883 1056Server and Daemon Utilities
1057
1058=item *
551e1d92 1059
f102b883 1060Archiving and Compression
1061
1062=item *
551e1d92 1063
f102b883 1064Images, Pixmap and Bitmap Manipulation, Drawing, and Graphing
1065
1066=item *
551e1d92 1067
f102b883 1068Mail and Usenet News
1069
1070=item *
551e1d92 1071
f102b883 1072Control Flow Utilities (callbacks and exceptions etc)
1073
1074=item *
551e1d92 1075
f102b883 1076File Handle and Input/Output Stream Utilities
1077
1078=item *
551e1d92 1079
f102b883 1080Miscellaneous Modules
1081
1082=back
1083
19799a22 1084Registered CPAN sites as of this writing include the following.
f102b883 1085You should try to choose one close to you:
1086
4e860d0a 1087=head2 Africa
1088
cea6626f 1089=over 4
f102b883 1090
4e860d0a 1091=item *
1092
1093South Africa
1094
1095 ftp://ftp.is.co.za/programming/perl/CPAN/
1096 ftp://ftp.saix.net/pub/CPAN/
1097 ftp://ftpza.co.za/pub/mirrors/cpan/
1098 ftp://ftp.sun.ac.za/CPAN/
1099
1100=back
1101
1102=head2 Asia
1103
1104=over 4
1105
1106=item *
1107
1108China
1109
1110 ftp://freesoft.cei.gov.cn/pub/languages/perl/CPAN/
1111 http://www2.linuxforum.net/mirror/CPAN/
1112 http://cpan.shellhung.org/
1113 ftp://ftp.shellhung.org/pub/CPAN
1114
1115=item *
1116
1117Hong Kong
1118
1119 http://CPAN.pacific.net.hk/
1120 ftp://ftp.pacific.net.hk/pub/mirror/CPAN/
1121
1122=item *
1123
1124Indonesia
1125
1126 http://piksi.itb.ac.id/CPAN/
1127 ftp://mirrors.piksi.itb.ac.id/CPAN/
1128 http://CPAN.mweb.co.id/
1129 ftp://ftp.mweb.co.id/pub/languages/perl/CPAN/
1130
1131=item *
1132
1133Israel
1134
1135 http://www.iglu.org.il:/pub/CPAN/
1136 ftp://ftp.iglu.org.il/pub/CPAN/
1137 http://bioinfo.weizmann.ac.il/pub/software/perl/CPAN/
1138 ftp://bioinfo.weizmann.ac.il/pub/software/perl/CPAN/
1139
1140=item *
1141
1142Japan
1143
1144 ftp://ftp.u-aizu.ac.jp/pub/lang/perl/CPAN/
1145 ftp://ftp.kddlabs.co.jp/CPAN/
1146 http://mirror.nucba.ac.jp/mirror/Perl/
1147 ftp://mirror.nucba.ac.jp/mirror/Perl/
1148 ftp://ftp.meisei-u.ac.jp/pub/CPAN/
1149 ftp://ftp.jaist.ac.jp/pub/lang/perl/CPAN/
1150 ftp://ftp.dti.ad.jp/pub/lang/CPAN/
1151 ftp://ftp.ring.gr.jp/pub/lang/perl/CPAN/
1152
1153=item *
1154
1155Saudi Arabia
1156
1157 ftp://ftp.isu.net.sa/pub/CPAN/
1158
1159=item *
1160
1161Singapore
1162
1163 http://cpan.hjc.edu.sg
1164 http://ftp.nus.edu.sg/unix/perl/CPAN/
1165 ftp://ftp.nus.edu.sg/pub/unix/perl/CPAN/
1166
1167=item *
1168
1169South Korea
1170
1171 http://CPAN.bora.net/
1172 ftp://ftp.bora.net/pub/CPAN/
1173 http://ftp.kornet.net/CPAN/
1174 ftp://ftp.kornet.net/pub/CPAN/
1175 ftp://ftp.nuri.net/pub/CPAN/
1176
1177=item *
1178
1179Taiwan
1180
1181 ftp://coda.nctu.edu.tw/UNIX/perl/CPAN
1182 ftp://ftp.ee.ncku.edu.tw/pub/perl/CPAN/
1183 ftp://ftp1.sinica.edu.tw/pub1/perl/CPAN/
1184
1185=item *
1186
1187Thailand
1188
1189 http://download.nectec.or.th/CPAN/
1190 ftp://ftp.nectec.or.th/pub/languages/CPAN/
1191 ftp://ftp.cs.riubon.ac.th/pub/mirrors/CPAN/
1192
1193=back
1194
1195=head2 Central America
1196
1197=over 4
1198
1199=item *
1200
1201Costa Rica
1202
1203 ftp://ftp.linux.co.cr/mirrors/CPAN/
1204 http://ftp.ucr.ac.cr/Unix/CPAN/
1205 ftp://ftp.ucr.ac.cr/pub/Unix/CPAN/
1206
1207=back
1208
1209=head2 Europe
1210
1211=over 4
1212
1213=item *
1214
1215Austria
1216
1217 ftp://ftp.tuwien.ac.at/pub/languages/perl/CPAN/
1218
1219=item *
1220
1221Belgium
1222
1223 http://ftp.easynet.be/CPAN/
1224 ftp://ftp.easynet.be/CPAN/
1225 ftp://ftp.kulnet.kuleuven.ac.be/pub/mirror/CPAN/
1226
1227=item *
1228
1229Bulgaria
1230
1231 ftp://ftp.ntrl.net/pub/mirrors/CPAN/
1232
1233=item *
1234
1235Croatia
1236
1237 ftp://ftp.linux.hr/pub/CPAN/
1238
1239=item *
1240
1241Czech Republic
1242
1243 http://www.fi.muni.cz/pub/perl/
1244 ftp://ftp.fi.muni.cz/pub/perl/
1245 ftp://sunsite.mff.cuni.cz/MIRRORS/ftp.funet.fi/pub/languages/perl/CPAN/
1246
1247=item *
1248
1249Denmark
1250
1251 ftp://sunsite.auc.dk/pub/languages/perl/CPAN/
1252 http://www.cpan.dk/CPAN/
1253 ftp://www.cpan.dk/ftp.cpan.org/CPAN/
1254
1255=item *
1256
1257England
1258
1259 http://www.mirror.ac.uk/sites/ftp.funet.fi/pub/languages/perl/CPAN
1260 ftp://ftp.mirror.ac.uk/sites/ftp.funet.fi/pub/languages/perl/CPAN/
1261 ftp://ftp.demon.co.uk/pub/mirrors/perl/CPAN/
1262 ftp://ftp.flirble.org/pub/languages/perl/CPAN/
1263 ftp://ftp.plig.org/pub/CPAN/
1264 ftp://sunsite.doc.ic.ac.uk/packages/CPAN/
1265 http://mirror.uklinux.net/CPAN/
1266 ftp://mirror.uklinux.net/pub/CPAN/
1267 ftp://usit.shef.ac.uk/pub/packages/CPAN/
1268
1269=item *
1270
1271Estonia
1272
1273 ftp://ftp.ut.ee/pub/languages/perl/CPAN/
1274
1275=item *
1276
1277Finland
1278
1279 ftp://ftp.funet.fi/pub/languages/perl/CPAN/
1280
1281=item *
1282
1283France
1284
1285 ftp://cpan.ftp.worldonline.fr/pub/CPAN/
1286 ftp://ftp.club-internet.fr/pub/perl/CPAN/
1287 ftp://ftp.lip6.fr/pub/perl/CPAN/
1288 ftp://ftp.oleane.net/pub/mirrors/CPAN/
1289 ftp://ftp.pasteur.fr/pub/computing/CPAN/
1290 ftp://cpan.cict.fr/pub/CPAN/
1291 ftp://ftp.uvsq.fr/pub/perl/CPAN/
1292
1293=item *
1294
1295Germany
1296
1297 ftp://ftp.rz.ruhr-uni-bochum.de/pub/CPAN/
1298 ftp://ftp.freenet.de/pub/ftp.cpan.org/pub/CPAN/
1299 ftp://ftp.uni-erlangen.de/pub/source/CPAN/
1300 ftp://ftp-stud.fht-esslingen.de/pub/Mirrors/CPAN
1301 ftp://ftp.gigabell.net/pub/CPAN/
1302 http://ftp.gwdg.de/pub/languages/perl/CPAN/
1303 ftp://ftp.gwdg.de/pub/languages/perl/CPAN/
1304 ftp://ftp.uni-hamburg.de/pub/soft/lang/perl/CPAN/
1305 ftp://ftp.leo.org/pub/comp/general/programming/languages/script/perl/CPAN/
1306 ftp://ftp.mpi-sb.mpg.de/pub/perl/CPAN/
1307 ftp://ftp.gmd.de/mirrors/CPAN/
1308
1309=item *
1310
1311Greece
1312
1313 ftp://ftp.forthnet.gr/pub/languages/perl/CPAN
1314 ftp://ftp.ntua.gr/pub/lang/perl/
1315
1316=item *
1317
1318Hungary
1319
1320 http://cpan.artifact.hu/
1321 ftp://cpan.artifact.hu/CPAN/
1322 ftp://ftp.kfki.hu/pub/packages/perl/CPAN/
1323
1324=item *
1325
1326Iceland
1327
1328 http://cpan.gm.is/
1329 ftp://ftp.gm.is/pub/CPAN/
1330
1331=item *
1332
1333Ireland
1334
1335 http://cpan.indigo.ie/
1336 ftp://cpan.indigo.ie/pub/CPAN/
1337 http://sunsite.compapp.dcu.ie/pub/perl/
1338 ftp://sunsite.compapp.dcu.ie/pub/perl/
1339
1340=item *
1341
1342Italy
1343
1344 http://cpan.nettuno.it/
1345 http://gusp.dyndns.org/CPAN/
1346 ftp://gusp.dyndns.org/pub/CPAN
1347 http://softcity.iol.it/cpan
1348 ftp://softcity.iol.it/pub/cpan
1349 ftp://ftp.unina.it/pub/Other/CPAN/
1350 ftp://ftp.unipi.it/pub/mirror/perl/CPAN/
1351 ftp://cis.uniRoma2.it/CPAN/
1352 ftp://ftp.edisontel.it/pub/CPAN_Mirror/
1353 ftp://ftp.flashnet.it/pub/CPAN/
1354
1355=item *
1356
1357Latvia
1358
1359 http://kvin.lv/pub/CPAN/
1360
1361=item *
1362
1363Netherlands
1364
1365 ftp://download.xs4all.nl/pub/mirror/CPAN/
1366 ftp://ftp.nl.uu.net/pub/CPAN/
1367 ftp://ftp.nluug.nl/pub/languages/perl/CPAN/
1368 ftp://ftp.cpan.nl/pub/CPAN/
1369 http://www.cs.uu.nl/mirror/CPAN/
1370 ftp://ftp.cs.uu.nl/mirror/CPAN/
1371
1372=item *
1373
1374Norway
1375
1376 ftp://sunsite.uio.no/pub/languages/perl/CPAN/
1377 ftp://ftp.uit.no/pub/languages/perl/cpan/
1378
1379=item *
1380
1381Poland
1382
1383 ftp://ftp.pk.edu.pl/pub/lang/perl/CPAN/
1384 ftp://ftp.mega.net.pl/pub/mirrors/ftp.perl.com/
1385 ftp://ftp.man.torun.pl/pub/doc/CPAN/
1386 ftp://sunsite.icm.edu.pl/pub/CPAN/
1387
1388=item *
1389
1390Portugal
1391
1392 ftp://ftp.ua.pt/pub/CPAN/
1393 ftp://perl.di.uminho.pt/pub/CPAN/
1394 ftp://ftp.ist.utl.pt/pub/CPAN/
1395 ftp://ftp.netc.pt/pub/CPAN/
1396
1397=item *
1398
1399Romania
1400
1401 ftp://archive.logicnet.ro/mirrors/ftp.cpan.org/CPAN/
1402 ftp://ftp.kappa.ro/pub/mirrors/ftp.perl.org/pub/CPAN/
1403 ftp://ftp.dntis.ro/pub/cpan/
1404 ftp://ftp.opsynet.com/cpan/
1405 ftp://ftp.dnttm.ro/pub/CPAN/
1406 ftp://ftp.timisoara.roedu.net/mirrors/CPAN/
1407
1408=item *
1409
1410Russia
1411
1412 ftp://ftp.chg.ru/pub/lang/perl/CPAN/
1413 http://cpan.rinet.ru/
1414 ftp://cpan.rinet.ru/pub/mirror/CPAN/
1415 ftp://ftp.aha.ru/pub/CPAN/
1416 ftp://ftp.sai.msu.su/pub/lang/perl/CPAN/
1417
1418=item *
1419
1420Slovakia
1421
1422 ftp://ftp.entry.sk/pub/languages/perl/CPAN/
1423
1424=item *
1425
1426Slovenia
1427
1428 ftp://ftp.arnes.si/software/perl/CPAN/
1429
1430=item *
1431
1432Spain
1433
1434 ftp://ftp.rediris.es/mirror/CPAN/
1435 ftp://ftp.etse.urv.es/pub/perl/
1436
1437=item *
1438
1439Sweden
1440
1441 http://ftp.du.se/CPAN/
1442 ftp://ftp.du.se/pub/CPAN/
1443 ftp://ftp.sunet.se/pub/lang/perl/CPAN/
1444
1445=item *
1446
1447Switzerland
1448
1449 ftp://ftp.danyk.ch/CPAN/
1450 ftp://sunsite.cnlab-switch.ch/mirror/CPAN/
1451
1452=item *
1453
1454Turkey
1455
1456 ftp://sunsite.bilkent.edu.tr/pub/languages/CPAN/
1457
1458=back
1459
1460=head2 North America
1461
1462=over 4
1463
1464=item *
1465
1466Canada
1467
1468=over 8
1469
1470=item *
1471
1472Alberta
1473
1474 http://sunsite.ualberta.ca/pub/Mirror/CPAN/
1475 ftp://sunsite.ualberta.ca/pub/Mirror/CPAN/
1476
1477=item *
1478
1479Manitoba
1480
1481 http://theoryx5.uwinnipeg.ca/pub/CPAN/
1482 ftp://theoryx5.uwinnipeg.ca/pub/CPAN/
1483
1484=item *
1485
1486Nova Scotia
1487
1488 ftp://cpan.chebucto.ns.ca/pub/CPAN/
1489
1490=item *
1491
1492Ontario
1493
1494 ftp://ftp.crc.ca/pub/packages/lang/perl/CPAN/
1495
1496=item *
1497
1498Mexico
1499
1500 http://www.msg.com.mx/CPAN/
1501 ftp://ftp.msg.com.mx/pub/CPAN/
1502
1503=back
1504
1505=item *
1506
1507United States
1508
1509=over 8
1510
1511=item *
1512
1513Alabama
1514
1515 http://mirror.hiwaay.net/CPAN/
1516 ftp://mirror.hiwaay.net/CPAN/
1517
1518=item *
1519
1520California
1521
1522 http://www.cpan.org/
1523 ftp://ftp.cpan.org/CPAN/
1524 ftp://cpan.nas.nasa.gov/pub/perl/CPAN/
1525 ftp://ftp.digital.com/pub/plan/perl/CPAN/
1526 http://www.kernel.org/pub/mirrors/cpan/
1527 ftp://ftp.kernel.org/pub/mirrors/cpan/
1528 http://www.perl.com/CPAN/
1529 http://download.sourceforge.net/mirrors/CPAN/
1530
1531=item *
1532
1533Colorado
1534
1535 ftp://ftp.cs.colorado.edu/pub/perl/CPAN/
1536
1537=item *
1538
1539Florida
1540
1541 ftp://ftp.cise.ufl.edu/pub/perl/CPAN/
1542
1543=item *
1544
1545Georgia
1546
1547 ftp://ftp.twoguys.org/CPAN/
1548
1549=item *
1550
1551Illinois
1552
1553 http://www.neurogames.com/mirrors/CPAN
1554 http://uiarchive.uiuc.edu/mirrors/ftp/ftp.cpan.org/pub/CPAN/
1555 ftp://uiarchive.uiuc.edu/mirrors/ftp/ftp.cpan.org/pub/CPAN/
1556
1557=item *
1558
1559Indiana
1560
1561 ftp://ftp.uwsg.indiana.edu/pub/perl/CPAN/
1562 http://cpan.nitco.com/
1563 ftp://cpan.nitco.com/pub/CPAN/
1564 ftp://cpan.in-span.net/
1565 http://csociety-ftp.ecn.purdue.edu/pub/CPAN
1566 ftp://csociety-ftp.ecn.purdue.edu/pub/CPAN
1567
1568=item *
1569
1570Kentucky
1571
1572 http://cpan.uky.edu/
1573 ftp://cpan.uky.edu/pub/CPAN/
1574
1575=item *
1576
1577Massachusetts
1578
1579 ftp://ftp.ccs.neu.edu/net/mirrors/ftp.funet.fi/pub/languages/perl/CPAN/
1580 ftp://ftp.iguide.com/pub/mirrors/packages/perl/CPAN/
1581
1582=item *
1583
1584New Jersey
1585
1586 ftp://ftp.cpanel.net/pub/CPAN/
1587
1588=item *
1589
1590New York
1591
1592 ftp://ftp.freesoftware.com/pub/perl/CPAN/
1593 http://www.deao.net/mirrors/CPAN/
1594 ftp://ftp.deao.net/pub/CPAN/
1595 ftp://ftp.stealth.net/pub/mirrors/ftp.cpan.org/pub/CPAN/
1596 http://mirror.nyc.anidea.com/CPAN/
1597 ftp://mirror.nyc.anidea.com/pub/CPAN/
1598 http://www.rge.com/pub/languages/perl/
1599 ftp://ftp.rge.com/pub/languages/perl/
1600 ftp://mirrors.cloud9.net/pub/mirrors/CPAN/
1601
1602=item *
1603
1604North Carolina
1605
1606 ftp://ftp.duke.edu/pub/perl/
1607
1608=item *
1609
1610Ohio
1611
1612 ftp://ftp.loaded.net/pub/CPAN/
1613
1614=item *
1615
1616Oklahoma
1617
1618 ftp://ftp.ou.edu/mirrors/CPAN/
1619
1620=item *
1621
1622Oregon
1623
1624 ftp://ftp.orst.edu/pub/packages/CPAN/
1625
1626=item *
1627
1628Pennsylvania
1629
1630 http://ftp.epix.net/CPAN/
1631 ftp://ftp.epix.net/pub/languages/perl/
1632 ftp://carroll.cac.psu.edu/pub/CPAN/
1633
1634=item *
1635
1636Tennessee
1637
1638 ftp://ftp.sunsite.utk.edu/pub/CPAN/
1639
1640=item *
1641
1642Texas
1643
1644 http://ftp.sedl.org/pub/mirrors/CPAN/
1645 http://jhcloos.com/pub/mirror/CPAN/
1646 ftp://jhcloos.com/pub/mirror/CPAN/
1647
1648=item *
1649
1650Utah
1651
1652 ftp://mirror.xmission.com/CPAN/
1653
1654=item *
1655
1656Virginia
1657
1658 http://mirrors.rcn.net/pub/lang/CPAN/
1659 ftp://mirrors.rcn.net/pub/lang/CPAN/
1660 ftp://ruff.cs.jmu.edu/pub/CPAN/
1661 http://perl.Liquidation.com/CPAN/
1662
1663=item *
1664
1665Washington
1666
1667 http://cpan.llarian.net/
1668 ftp://cpan.llarian.net/pub/CPAN/
1669 ftp://ftp-mirror.internap.com/pub/CPAN/
1670 ftp://ftp.spu.edu/pub/CPAN/
1671
1672=back
1673
1674=back
1675
1676=head2 Oceania
1677
1678=over 4
1679
1680=item *
1681
1682Australia
1683
1684 http://ftp.planetmirror.com/pub/CPAN/
1685 ftp://ftp.planetmirror.com/pub/CPAN/
1686 ftp://mirror.aarnet.edu.au/pub/perl/CPAN/
1687 ftp://cpan.topend.com.au/pub/CPAN/
1688
1689=item *
1690
1691New Zealand
1692
1693 ftp://ftp.auckland.ac.nz/pub/perl/CPAN/
1694
1695=back
1696
1697=head2 South America
1698
1699=over 4
1700
1701=item *
1702
1703Argentina
1704
1705 ftp://mirrors.bannerlandia.com.ar/mirrors/CPAN/
1706
1707=item *
1708
1709Brazil
1710
1711 ftp://cpan.pop-mg.com.br/pub/CPAN/
1712 ftp://ftp.matrix.com.br/pub/perl/
1713 ftp://cpan.if.usp.br/pub/mirror/CPAN/
1714
1715=item *
1716
1717Chile
1718
1719 ftp://ftp.psinet.cl/pub/programming/perl/CPAN/
1720 ftp://sunsite.dcc.uchile.cl/pub/lang/perl/
f102b883 1721
1722=back
1723
1724For an up-to-date listing of CPAN sites,
4e860d0a 1725see http://www.cpan.org/SITES or ftp://www.cpan.org/SITES .
f102b883 1726
1727=head1 Modules: Creation, Use, and Abuse
1728
1729(The following section is borrowed directly from Tim Bunce's modules
1730file, available at your nearest CPAN site.)
1731
1732Perl implements a class using a package, but the presence of a
1733package doesn't imply the presence of a class. A package is just a
1734namespace. A class is a package that provides subroutines that can be
1735used as methods. A method is just a subroutine that expects, as its
1736first argument, either the name of a package (for "static" methods),
1737or a reference to something (for "virtual" methods).
1738
1739A module is a file that (by convention) provides a class of the same
1740name (sans the .pm), plus an import method in that class that can be
1741called to fetch exported symbols. This module may implement some of
1742its methods by loading dynamic C or C++ objects, but that should be
1743totally transparent to the user of the module. Likewise, the module
1744might set up an AUTOLOAD function to slurp in subroutine definitions on
1745demand, but this is also transparent. Only the F<.pm> file is required to
2e1d04bc 1746exist. See L<perlsub>, L<perltoot>, and L<AutoLoader> for details about
f102b883 1747the AUTOLOAD mechanism.
1748
1749=head2 Guidelines for Module Creation
1750
1751=over 4
1752
4e860d0a 1753=item *
1754
1755Do similar modules already exist in some form?
f102b883 1756
1757If so, please try to reuse the existing modules either in whole or
1758by inheriting useful features into a new class. If this is not
1759practical try to get together with the module authors to work on
1760extending or enhancing the functionality of the existing modules.
1761A perfect example is the plethora of packages in perl4 for dealing
1762with command line options.
1763
1764If you are writing a module to expand an already existing set of
1765modules, please coordinate with the author of the package. It
1766helps if you follow the same naming scheme and module interaction
1767scheme as the original author.
1768
4e860d0a 1769=item *
1770
1771Try to design the new module to be easy to extend and reuse.
f102b883 1772
9f1b1f2d 1773Try to C<use warnings;> (or C<use warnings qw(...);>).
1774Remember that you can add C<no warnings qw(...);> to individual blocks
2e1d04bc 1775of code that need less warnings.
19799a22 1776
f102b883 1777Use blessed references. Use the two argument form of bless to bless
1778into the class name given as the first parameter of the constructor,
1779e.g.,:
1780
1781 sub new {
2e1d04bc 1782 my $class = shift;
1783 return bless {}, $class;
f102b883 1784 }
1785
1786or even this if you'd like it to be used as either a static
1787or a virtual method.
1788
1789 sub new {
2e1d04bc 1790 my $self = shift;
1791 my $class = ref($self) || $self;
1792 return bless {}, $class;
f102b883 1793 }
1794
1795Pass arrays as references so more parameters can be added later
1796(it's also faster). Convert functions into methods where
1797appropriate. Split large methods into smaller more flexible ones.
1798Inherit methods from other modules if appropriate.
1799
1800Avoid class name tests like: C<die "Invalid" unless ref $ref eq 'FOO'>.
19799a22 1801Generally you can delete the C<eq 'FOO'> part with no harm at all.
f102b883 1802Let the objects look after themselves! Generally, avoid hard-wired
1803class names as far as possible.
1804
c47ff5f1 1805Avoid C<< $r->Class::func() >> where using C<@ISA=qw(... Class ...)> and
1806C<< $r->func() >> would work (see L<perlbot> for more details).
f102b883 1807
1808Use autosplit so little used or newly added functions won't be a
5a964f20 1809burden to programs that don't use them. Add test functions to
f102b883 1810the module after __END__ either using AutoSplit or by saying:
1811
1812 eval join('',<main::DATA>) || die $@ unless caller();
1813
1814Does your module pass the 'empty subclass' test? If you say
19799a22 1815C<@SUBCLASS::ISA = qw(YOURCLASS);> your applications should be able
f102b883 1816to use SUBCLASS in exactly the same way as YOURCLASS. For example,
1817does your application still work if you change: C<$obj = new YOURCLASS;>
1818into: C<$obj = new SUBCLASS;> ?
1819
1820Avoid keeping any state information in your packages. It makes it
1821difficult for multiple other packages to use yours. Keep state
1822information in objects.
1823
2e1d04bc 1824Always use B<-w>.
19799a22 1825
1826Try to C<use strict;> (or C<use strict qw(...);>).
f102b883 1827Remember that you can add C<no strict qw(...);> to individual blocks
2e1d04bc 1828of code that need less strictness.
19799a22 1829
2e1d04bc 1830Always use B<-w>.
19799a22 1831
f102b883 1832Follow the guidelines in the perlstyle(1) manual.
1833
19799a22 1834Always use B<-w>.
1835
4e860d0a 1836=item *
1837
1838Some simple style guidelines
f102b883 1839
5a964f20 1840The perlstyle manual supplied with Perl has many helpful points.
f102b883 1841
1842Coding style is a matter of personal taste. Many people evolve their
1843style over several years as they learn what helps them write and
1844maintain good code. Here's one set of assorted suggestions that
1845seem to be widely used by experienced developers:
1846
1847Use underscores to separate words. It is generally easier to read
1848$var_names_like_this than $VarNamesLikeThis, especially for
1849non-native speakers of English. It's also a simple rule that works
1850consistently with VAR_NAMES_LIKE_THIS.
1851
1852Package/Module names are an exception to this rule. Perl informally
1853reserves lowercase module names for 'pragma' modules like integer
1854and strict. Other modules normally begin with a capital letter and
1855use mixed case with no underscores (need to be short and portable).
1856
1857You may find it helpful to use letter case to indicate the scope
1858or nature of a variable. For example:
1859
5a964f20 1860 $ALL_CAPS_HERE constants only (beware clashes with Perl vars)
f102b883 1861 $Some_Caps_Here package-wide global/static
1862 $no_caps_here function scope my() or local() variables
1863
1864Function and method names seem to work best as all lowercase.
c47ff5f1 1865e.g., C<< $obj->as_string() >>.
f102b883 1866
1867You can use a leading underscore to indicate that a variable or
1868function should not be used outside the package that defined it.
1869
4e860d0a 1870=item *
1871
1872Select what to export.
f102b883 1873
1874Do NOT export method names!
1875
1876Do NOT export anything else by default without a good reason!
1877
1878Exports pollute the namespace of the module user. If you must
1879export try to use @EXPORT_OK in preference to @EXPORT and avoid
1880short or common names to reduce the risk of name clashes.
1881
1882Generally anything not exported is still accessible from outside the
c47ff5f1 1883module using the ModuleName::item_name (or C<< $blessed_ref->method >>)
f102b883 1884syntax. By convention you can use a leading underscore on names to
1885indicate informally that they are 'internal' and not for public use.
1886
1887(It is actually possible to get private functions by saying:
1888C<my $subref = sub { ... }; &$subref;>. But there's no way to call that
1889directly as a method, because a method must have a name in the symbol
1890table.)
1891
1892As a general rule, if the module is trying to be object oriented
1893then export nothing. If it's just a collection of functions then
1894@EXPORT_OK anything but use @EXPORT with caution.
1895
4e860d0a 1896=item *
1897
1898Select a name for the module.
f102b883 1899
1900This name should be as descriptive, accurate, and complete as
1901possible. Avoid any risk of ambiguity. Always try to use two or
1902more whole words. Generally the name should reflect what is special
1903about what the module does rather than how it does it. Please use
1904nested module names to group informally or categorize a module.
1905There should be a very good reason for a module not to have a nested name.
1906Module names should begin with a capital letter.
1907
1908Having 57 modules all called Sort will not make life easy for anyone
1909(though having 23 called Sort::Quick is only marginally better :-).
1910Imagine someone trying to install your module alongside many others.
1911If in any doubt ask for suggestions in comp.lang.perl.misc.
1912
1913If you are developing a suite of related modules/classes it's good
1914practice to use nested classes with a common prefix as this will
1915avoid namespace clashes. For example: Xyz::Control, Xyz::View,
1916Xyz::Model etc. Use the modules in this list as a naming guide.
1917
1918If adding a new module to a set, follow the original author's
1919standards for naming modules and the interface to methods in
1920those modules.
1921
165c0277 1922If developing modules for private internal or project specific use,
1923that will never be released to the public, then you should ensure
1924that their names will not clash with any future public module. You
1925can do this either by using the reserved Local::* category or by
1926using a category name that includes an underscore like Foo_Corp::*.
1927
f102b883 1928To be portable each component of a module name should be limited to
192911 characters. If it might be used on MS-DOS then try to ensure each is
1930unique in the first 8 characters. Nested modules make this easier.
1931
4e860d0a 1932=item *
1933
1934Have you got it right?
f102b883 1935
1936How do you know that you've made the right decisions? Have you
1937picked an interface design that will cause problems later? Have
1938you picked the most appropriate name? Do you have any questions?
1939
1940The best way to know for sure, and pick up many helpful suggestions,
1941is to ask someone who knows. Comp.lang.perl.misc is read by just about
1942all the people who develop modules and it's the best place to ask.
1943
1944All you need to do is post a short summary of the module, its
1945purpose and interfaces. A few lines on each of the main methods is
1946probably enough. (If you post the whole module it might be ignored
1947by busy people - generally the very people you want to read it!)
1948
1949Don't worry about posting if you can't say when the module will be
1950ready - just say so in the message. It might be worth inviting
1951others to help you, they may be able to complete it for you!
1952
4e860d0a 1953=item *
1954
1955README and other Additional Files.
f102b883 1956
1957It's well known that software developers usually fully document the
1958software they write. If, however, the world is in urgent need of
1959your software and there is not enough time to write the full
1960documentation please at least provide a README file containing:
1961
1962=over 10
1963
1964=item *
4e860d0a 1965
f102b883 1966A description of the module/package/extension etc.
1967
1968=item *
4e860d0a 1969
f102b883 1970A copyright notice - see below.
1971
1972=item *
4e860d0a 1973
f102b883 1974Prerequisites - what else you may need to have.
1975
1976=item *
4e860d0a 1977
f102b883 1978How to build it - possible changes to Makefile.PL etc.
1979
1980=item *
4e860d0a 1981
f102b883 1982How to install it.
1983
1984=item *
4e860d0a 1985
f102b883 1986Recent changes in this release, especially incompatibilities
1987
1988=item *
4e860d0a 1989
f102b883 1990Changes / enhancements you plan to make in the future.
1991
1992=back
1993
1994If the README file seems to be getting too large you may wish to
1995split out some of the sections into separate files: INSTALL,
1996Copying, ToDo etc.
1997
1998=over 4
1999
2000=item Adding a Copyright Notice.
2001
4e860d0a 2002
f102b883 2003How you choose to license your work is a personal decision.
2004The general mechanism is to assert your Copyright and then make
2005a declaration of how others may copy/use/modify your work.
2006
2007Perl, for example, is supplied with two types of licence: The GNU
2008GPL and The Artistic Licence (see the files README, Copying, and
2009Artistic). Larry has good reasons for NOT just using the GNU GPL.
2010
2011My personal recommendation, out of respect for Larry, Perl, and the
5a964f20 2012Perl community at large is to state something simply like:
f102b883 2013
2014 Copyright (c) 1995 Your Name. All rights reserved.
2015 This program is free software; you can redistribute it and/or
2016 modify it under the same terms as Perl itself.
2017
2018This statement should at least appear in the README file. You may
2019also wish to include it in a Copying file and your source files.
2020Remember to include the other words in addition to the Copyright.
2021
4e860d0a 2022=item *
2023
2024Give the module a version/issue/release number.
f102b883 2025
2026To be fully compatible with the Exporter and MakeMaker modules you
2027should store your module's version number in a non-my package
2028variable called $VERSION. This should be a floating point
2029number with at least two digits after the decimal (i.e., hundredths,
2030e.g, C<$VERSION = "0.01">). Don't use a "1.3.2" style version.
19799a22 2031See L<Exporter> for details.
f102b883 2032
2033It may be handy to add a function or method to retrieve the number.
2034Use the number in announcements and archive file names when
2035releasing the module (ModuleName-1.02.tar.Z).
2036See perldoc ExtUtils::MakeMaker.pm for details.
2037
4e860d0a 2038=item *
2039
2040How to release and distribute a module.
f102b883 2041
2042It's good idea to post an announcement of the availability of your
2043module (or the module itself if small) to the comp.lang.perl.announce
2044Usenet newsgroup. This will at least ensure very wide once-off
2045distribution.
2046
2e1d04bc 2047If possible, register the module with CPAN. You should
f102b883 2048include details of its location in your announcement.
2049
2050Some notes about ftp archives: Please use a long descriptive file
5a964f20 2051name that includes the version number. Most incoming directories
f102b883 2052will not be readable/listable, i.e., you won't be able to see your
2053file after uploading it. Remember to send your email notification
2054message as soon as possible after uploading else your file may get
2055deleted automatically. Allow time for the file to be processed
2056and/or check the file has been processed before announcing its
2057location.
2058
2059FTP Archives for Perl Modules:
2060
6cecdcac 2061Follow the instructions and links on:
f102b883 2062
4e860d0a 2063 http://www.cpan.org/modules/00modlist.long.html
2064 http://www.cpan.org/modules/04pause.html
f102b883 2065
2066or upload to one of these sites:
2067
6cecdcac 2068 https://pause.kbx.de/pause/
2069 http://pause.perl.org/pause/
f102b883 2070
6cecdcac 2071and notify <modules@perl.org>.
f102b883 2072
2073By using the WWW interface you can ask the Upload Server to mirror
2074your modules from your ftp or WWW site into your own directory on
2075CPAN!
2076
2077Please remember to send me an updated entry for the Module list!
2078
4e860d0a 2079=item *
2080
2081Take care when changing a released module.
f102b883 2082
7b8d334a 2083Always strive to remain compatible with previous released versions.
2084Otherwise try to add a mechanism to revert to the
19799a22 2085old behavior if people rely on it. Document incompatible changes.
f102b883 2086
2087=back
2088
2089=back
2090
2091=head2 Guidelines for Converting Perl 4 Library Scripts into Modules
2092
2093=over 4
2094
4e860d0a 2095=item *
2096
2097There is no requirement to convert anything.
f102b883 2098
2099If it ain't broke, don't fix it! Perl 4 library scripts should
2100continue to work with no problems. You may need to make some minor
2101changes (like escaping non-array @'s in double quoted strings) but
2102there is no need to convert a .pl file into a Module for just that.
2103
4e860d0a 2104=item *
2105
2106Consider the implications.
f102b883 2107
5a964f20 2108All Perl applications that make use of the script will need to
f102b883 2109be changed (slightly) if the script is converted into a module. Is
2110it worth it unless you plan to make other changes at the same time?
2111
4e860d0a 2112=item *
2113
2114Make the most of the opportunity.
f102b883 2115
2116If you are going to convert the script to a module you can use the
19799a22 2117opportunity to redesign the interface. The guidelines for module
2118creation above include many of the issues you should consider.
f102b883 2119
4e860d0a 2120=item *
2121
2122The pl2pm utility will get you started.
f102b883 2123
2124This utility will read *.pl files (given as parameters) and write
2125corresponding *.pm files. The pl2pm utilities does the following:
2126
2127=over 10
2128
2129=item *
4e860d0a 2130
f102b883 2131Adds the standard Module prologue lines
2132
2133=item *
4e860d0a 2134
f102b883 2135Converts package specifiers from ' to ::
2136
2137=item *
4e860d0a 2138
f102b883 2139Converts die(...) to croak(...)
2140
2141=item *
4e860d0a 2142
f102b883 2143Several other minor changes
2144
2145=back
2146
2147Being a mechanical process pl2pm is not bullet proof. The converted
2148code will need careful checking, especially any package statements.
2149Don't delete the original .pl file till the new .pm one works!
2150
2151=back
2152
2153=head2 Guidelines for Reusing Application Code
2154
2155=over 4
2156
4e860d0a 2157=item *
551e1d92 2158
2159Complete applications rarely belong in the Perl Module Library.
f102b883 2160
4e860d0a 2161=item *
551e1d92 2162
2163Many applications contain some Perl code that could be reused.
f102b883 2164
2165Help save the world! Share your code in a form that makes it easy
2166to reuse.
2167
4e860d0a 2168=item *
551e1d92 2169
2170Break-out the reusable code into one or more separate module files.
f102b883 2171
4e860d0a 2172=item *
551e1d92 2173
2174Take the opportunity to reconsider and redesign the interfaces.
2175
4e860d0a 2176=item *
f102b883 2177
551e1d92 2178In some cases the 'application' can then be reduced to a small
f102b883 2179
2180fragment of code built on top of the reusable modules. In these cases
2181the application could invoked as:
2182
5a964f20 2183 % perl -e 'use Module::Name; method(@ARGV)' ...
f102b883 2184or
5a964f20 2185 % perl -mModule::Name ... (in perl5.002 or higher)
f102b883 2186
2187=back
2188
2189=head1 NOTE
2190
2191Perl does not enforce private and public parts of its modules as you may
2192have been used to in other languages like C++, Ada, or Modula-17. Perl
2193doesn't have an infatuation with enforced privacy. It would prefer
2194that you stayed out of its living room because you weren't invited, not
2195because it has a shotgun.
2196
2197The module and its user have a contract, part of which is common law,
2198and part of which is "written". Part of the common law contract is
2199that a module doesn't pollute any namespace it wasn't asked to. The
2200written contract for the module (A.K.A. documentation) may make other
2201provisions. But then you know when you C<use RedefineTheWorld> that
2202you're redefining the world and willing to take the consequences.