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Diffstat (limited to 'pod/perlmod.pod')
| -rw-r--r-- | pod/perlmod.pod | 265 |
1 files changed, 174 insertions, 91 deletions
diff --git a/pod/perlmod.pod b/pod/perlmod.pod index 7cb3a4907e..4fb5ec838b 100644 --- a/pod/perlmod.pod +++ b/pod/perlmod.pod @@ -13,11 +13,11 @@ Perl. The package statement declares the compilation unit as being in the given namespace. The scope of the package declaration is from the declaration itself through the end of the enclosing block (the same scope as the local() operator). All further unqualified dynamic identifiers -will be in this namespace. A package statement only affects dynamic +will be in this namespace. A package statement affects only dynamic variables--including those you've used local() on--but I<not> lexical variables created with my(). Typically it would be the first declaration in a file to be included by the C<require> or C<use> operator. You can -switch into a package in more than one place; it merely influences which +switch into a package in more than one place; it influences merely which symbol table is used by the compiler for the rest of that block. You can refer to variables and filehandles in other packages by prefixing the identifier with the package name and a double colon: @@ -39,10 +39,10 @@ It would treat package C<INNER> as a totally separate global package. Only identifiers starting with letters (or underscore) are stored in a package's symbol table. All other symbols are kept in package C<main>, including all of the punctuation variables like $_. In addition, the -identifiers STDIN, STDOUT, STDERR, ARGV, ARGVOUT, ENV, INC and SIG are +identifiers STDIN, STDOUT, STDERR, ARGV, ARGVOUT, ENV, INC, and SIG are forced to be in package C<main>, even when used for other purposes than their built-in one. Note also that, if you have a package called C<m>, -C<s> or C<y>, then you can't use the qualified form of an identifier +C<s>, or C<y>, then you can't use the qualified form of an identifier because it will be interpreted instead as a pattern match, a substitution, or a translation. @@ -62,7 +62,7 @@ temporarily switches back to the C<main> package to evaluate various expressions in the context of the C<main> package (or wherever you came from). See L<perldebug>. -See L<perlsub> for other scoping issues related to my() and local(), +See L<perlsub> for other scoping issues related to my() and local(), or L<perlref> regarding closures. =head2 Symbol Tables @@ -119,9 +119,9 @@ Assignment to a typeglob performs an aliasing operation, i.e., *dick = *richard; -causes variables, subroutines and file handles accessible via the +causes variables, subroutines, and file handles accessible via the identifier C<richard> to also be accessible via the identifier C<dick>. If -you only want to alias a particular variable or subroutine, you can +you want to alias only a particular variable or subroutine, you can assign a reference instead: *dick = \$richard; @@ -140,10 +140,10 @@ thing. # now use %hashsym normally, and you # will affect the caller's %another_hash my %nhash = (); # do what you want - return \%nhash; + return \%nhash; } -On return, the reference wil overwrite the hash slot in the +On return, the reference will overwrite the hash slot in the symbol table specified by the *some_hash typeglob. This is a somewhat tricky way of passing around references cheaply when you won't want to have to remember to dereference variables @@ -197,7 +197,7 @@ order of definition; that is: last in, first out (LIFO). Inside an C<END> subroutine C<$?> contains the value that the script is going to pass to C<exit()>. You can modify C<$?> to change the exit -value of the script. Beware of changing C<$?> by accident (eg, by +value of the script. Beware of changing C<$?> by accident (e.g.,, by running something via C<system>). Note that when you use the B<-n> and B<-p> switches to Perl, C<BEGIN> @@ -208,7 +208,7 @@ and C<END> work just as they do in B<awk>, as a degenerate case. There is no special class syntax in Perl, but a package may function as a class if it provides subroutines that function as methods. Such a package may also derive some of its methods from another class package -by listing the other package name in its @ISA array. +by listing the other package name in its @ISA array. For more on this, see L<perlobj>. @@ -225,15 +225,18 @@ symbols. Or it can do a little of both. For example, to start a normal module called Fred, create a file called Fred.pm and put this at the start of it: - package Fred; - use Exporter (); + package Fred; + use strict; + use Exporter (); + use vars qw(@ISA @EXPORT @EXPORT_OK); @ISA = qw(Exporter); - @EXPORT = qw(func1 func2); - @EXPORT_OK = qw($sally @listabob %harry func3); + @EXPORT = qw(&func1 &func2); + @EXPORT_OK = qw($sally @listabob %harry &func3); + use vars qw($sally @listabob %harry); Then go on to declare and use your variables in functions without any qualifications. -See L<Exporter> and the I<Perl Modules File> for details on +See L<Exporter> and the I<Perl Modules File> for details on mechanics and style issues in module creation. Perl modules are included into your program by saying @@ -278,7 +281,7 @@ instead of C<use>. With require you can get into this problem: require Cwd; # make Cwd:: accessible $here = Cwd::getcwd(); - use Cwd; # import names from Cwd:: + use Cwd; # import names from Cwd:: $here = getcwd(); require Cwd; # make Cwd:: accessible @@ -299,7 +302,7 @@ the module. If so, these will be entirely transparent to the user of the module. It is the responsibility of the F<.pm> file to load (or arrange to autoload) any additional functionality. The POSIX module happens to do both dynamic loading and autoloading, but the user can -just say C<use POSIX> to get it all. +say just C<use POSIX> to get it all. For more information on writing extension modules, see L<perlxs> and L<perlguts>. @@ -315,14 +318,14 @@ 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 (AKA documentation) may make other +written contract for the module (A.K.A. documentation) may make other provisions. But then you know when you C<use RedefineTheWorld> that you're redefining the world and willing to take the consequences. =head1 THE PERL MODULE LIBRARY -A number of modules are included the the Perl distribution. These are -described below, and all end in F<.pm>. You may also discover files in +A number of modules are included the Perl distribution. These are +described below, and all end in F<.pm>. You may also discover files in the library directory that end in either F<.pl> or F<.ph>. These are old libraries supplied so that old programs that use them still run. The F<.pl> files will all eventually be converted into standard modules, and @@ -334,7 +337,7 @@ conversion, but it's just a mechanical process, so is far from bulletproof. =head2 Pragmatic Modules They work somewhat like pragmas in that they tend to affect the compilation of -your program, and thus will usually only work well when used within a +your program, and thus will usually work well only when used within a C<use>, or C<no>. Most of these are locally scoped, so an inner BLOCK may countermand any of these by saying: @@ -343,7 +346,7 @@ may countermand any of these by saying: which lasts until the end of that BLOCK. -Unlike the pragrmas that effect the C<$^H> hints variable, the C<use +Unlike the pragmas that effect the C<$^H> hints variable, the C<use vars> and C<use subs> declarations are not BLOCK-scoped. They allow you to pre-declare a variables or subroutines within a particular <I>file</I> rather than just a block. Such declarations are effective @@ -354,6 +357,11 @@ The following pragmas are defined (and have their own documentation). =over 12 +=item blib + +manipulate @INC at compile time to use MakeMaker's uninstalled version +of a package + =item diagnostics force verbose warning diagnostics @@ -370,13 +378,17 @@ request less of something from the compiler manipulate @INC at compile time +=item locale + +use or ignore current locale for built-in operations (see L<perli18n>) + =item ops -restrict unsafe operations when compiling +restrict named opcodes when compiling or running Perl code =item overload -package for overloading perl operations +overload basic Perl operations =item sigtrap @@ -388,11 +400,11 @@ restrict unsafe constructs =item subs -predeclare sub names +pre-declare sub names =item vars -predeclare global variable names +pre-declare global variable names =back @@ -424,6 +436,10 @@ benchmark running times of code warn of errors (from perspective of caller) +=item Class::Template + +struct/member template builder + =item Config access Perl configuration information @@ -446,7 +462,7 @@ supply object methods for directory handles =item DynaLoader -Dynamically load C libraries into Perl code +dynamically load C libraries into Perl code =item English @@ -462,7 +478,7 @@ implements default import method for modules =item ExtUtils::Embed -Utilities for embedding Perl in C/C++ applications +utilities for embedding Perl in C/C++ applications =item ExtUtils::Install @@ -472,6 +488,18 @@ install files from here to there determine libraries to use and how to use them +=item ExtUtils::MM_OS2 + +methods to override UN*X behaviour in ExtUtils::MakeMaker + +=item ExtUtils::MM_Unix + +methods used by ExtUtils::MakeMaker + +=item ExtUtils::MM_VMS + +methods to override UN*X behaviour in ExtUtils::MakeMaker + =item ExtUtils::MakeMaker create an extension Makefile @@ -480,10 +508,6 @@ create an extension Makefile utilities to write and check a MANIFEST file -=item ExtUtils::Miniperl - -write the C code for perlmain.c - =item ExtUtils::Mkbootstrap make a bootstrap file for use by DynaLoader @@ -492,21 +516,21 @@ make a bootstrap file for use by DynaLoader write linker options files for dynamic extension -=item ExtUtils::MM_OS2 +=item ExtUtils::testlib -methods to override UN*X behaviour in ExtUtils::MakeMaker +add blib/* directories to @INC -=item ExtUtils::MM_Unix +=item CPAN -methods used by ExtUtils::MakeMaker +interface to Comprehensive Perl Archive Network -=item ExtUtils::MM_VMS +=item CPAN::FirstTime -methods to override UN*X behaviour in ExtUtils::MakeMaker +create a CPAN configuration file -=item ExtUtils::testlib +=item CPAN::Nox -add blib/* directories to @INC +run CPAN while avoiding compiled extensions =item Fatal @@ -518,39 +542,47 @@ load the C Fcntl.h defines =item File::Basename -parse file specifications - -=item FileCache - -keep more files open than the system permits +split a pathname into pieces =item File::CheckTree run many filetest checks on a tree +=item File::Compare + +compare files or filehandles + =item File::Copy -Copy files or filehandles +copy files or filehandles =item File::Find traverse a file tree -=item FileHandle - -supply object methods for filehandles - =item File::Path create or remove a series of directories +=item File::stat + +by-name interface to Perl's built-in stat() functions + +=item FileCache + +keep more files open than the system permits + +=item FileHandle + +supply object methods for filehandles + =item FindBin locate directory of original perl script =item GDBM_File -access to the gdbm library. +access to the gdbm library =item Getopt::Long @@ -616,13 +648,41 @@ complex numbers and associated mathematical functions tied access to ndbm files +=item Net::FTP + +File Transfer Protocol client + =item Net::Ping check a host for upness +=item Net::Netrc + +parser for ".netrc" files a la Berkeley UNIX + +=item Net::Socket + +support class for Net::FTP + +=item Net::hostent + +by-name interface to Perl's built-in gethost*() functions + +=item Net::netent + +by-name interface to Perl's built-in getnet*() functions + +=item Net::protoent + +by-name interface to Perl's built-in getproto*() functions + +=item Net::servent + +by-name interface to Perl's built-in getserv*() functions + =item Opcode -disable named opcodes when compiling perl code +disable named opcodes when compiling or running perl code =item Pod::Text @@ -630,16 +690,16 @@ convert POD data to formatted ASCII text =item POSIX -interface to IEEE Std 1003.1 - -=item Safe - -compile and execute code in restricted compartments +interface to IEEE Standard 1003.1 =item SDBM_File tied access to sdbm files +=item Safe + +compile and execute code in restricted compartments + =item Search::Dict search for key in dictionary file @@ -674,7 +734,7 @@ interface to the UNIX syslog(3) calls =item Term::Cap -Perl termcap interface +termcap interface =item Term::Complete @@ -682,7 +742,7 @@ word completion module =item Term::ReadLine -interface to various readline packages. +interface to various C<readline> packages =item Test::Harness @@ -698,7 +758,7 @@ parse text into an array of tokens =item Text::Soundex -implementation of the Soundex Algorithm as Described by Knuth +implementation of the Soundex Algorithm as described by Knuth =item Text::Tabs @@ -712,6 +772,10 @@ line wrapping to form simple paragraphs base class definitions for tied hashes +=item Tie::RefHash + +base class definitions for tied hashes with references as keys + =item Tie::Scalar base class definitions for tied scalars @@ -724,10 +788,30 @@ fixed-table-size, fixed-key-length hashing efficiently compute time from local and GMT time +=item Time::gmtime + +by-name interface to Perl's built-in gmtime() function + +=item Time::localtime + +by-name interface to Perl's built-in localtime() function + +=item Time::tm + +internal object used by Time::gmtime and Time::localtime + =item UNIVERSAL base class for ALL classes (blessed references) +=item User::grent + +by-name interface to Perl's built-in getgr*() functions + +=item User::pwent + +by-name interface to Perl's built-in getpw*() functions + =back To find out I<all> the modules installed on your system, including @@ -745,7 +829,7 @@ 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 size, volatility, or simply lack of time for +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 @@ -755,13 +839,13 @@ disposition. =head1 CPAN CPAN stands for the Comprehensive Perl Archive Network. This is a globally -replicated collection of all known Perl materials, including hundreds +replicated collection of all known Perl materials, including hundreds of unbundled modules. Here are the major categories of modules: =over =item * -Language Extensions and Documentation Tools +Language Extensions and Documentation Tools =item * Development Support @@ -788,16 +872,16 @@ Interfaces to / Emulations of Other Programming Languages File Names, File Systems and File Locking (see also File Handles) =item * -String Processing, Language Text Processing, Parsing and Searching +String Processing, Language Text Processing, Parsing, and Searching =item * -Option, Argument, Parameter and Configuration File Processing +Option, Argument, Parameter, and Configuration File Processing =item * Internationalization and Locale =item * -Authentication, Security and Encryption +Authentication, Security, and Encryption =item * World Wide Web, HTML, HTTP, CGI, MIME @@ -809,7 +893,7 @@ Server and Daemon Utilities Archiving and Compression =item * -Images, Pixmap and Bitmap Manipulation, Drawing and Graphing +Images, Pixmap and Bitmap Manipulation, Drawing, and Graphing =item * Mail and Usenet News @@ -898,15 +982,15 @@ ftp://ftp.is.co.za/programming/perl/CPAN/ =back -For an up-to-date listing of CPAN sites, +For an up-to-date listing of CPAN sites, see F<http://www.perl.com/perl/CPAN> or F<ftp://ftp.perl.com/perl/>. -=head1 Modules: Creation, Use and Abuse +=head1 Modules: Creation, Use, and Abuse (The following section is borrowed directly from Tim Bunce's modules file, available at your nearest CPAN site.) -Perl 5 implements a class using a package, but the presence of a +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 @@ -944,9 +1028,9 @@ scheme as the original author. 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.: +e.g.,: - sub new { + sub new { my $class = shift; return bless {}, $class; } @@ -954,7 +1038,7 @@ e.g.: or even this if you'd like it to be used as either a static or a virtual method. - sub new { + sub new { my $self = shift; my $class = ref($self) || $self; return bless {}, $class; @@ -1021,7 +1105,7 @@ or nature of a variable. For example: $no_caps_here function scope my() or local() variables Function and method names seem to work best as all lowercase. -E.g., C<$obj-E<gt>as_string()>. +e.g.,, C<$obj-E<gt>as_string()>. You can use a leading underscore to indicate that a variable or function should not be used outside the package that defined it. @@ -1039,11 +1123,11 @@ short or common names to reduce the risk of name clashes. Generally anything not exported is still accessible from outside the module using the ModuleName::item_name (or C<$blessed_ref-E<gt>method>) syntax. By convention you can use a leading underscore on names to -informally indicate that they are 'internal' and not for public use. +indicate informally that they are 'internal' and not for public use. (It is actually possible to get private functions by saying: C<my $subref = sub { ... }; &$subref;>. But there's no way to call that -directly as a method, since a method must have a name in the symbol +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 @@ -1052,12 +1136,12 @@ then export nothing. If it's just a collection of functions then =item Select a name for the module. -This name should be as descriptive, accurate and complete as +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 informally group or categorise a module. -A module should have a very good reason not to have a nested name. +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 @@ -1137,16 +1221,16 @@ Copying, ToDo etc. =item Adding a Copyright Notice. -How you choose to licence your work is a personal decision. +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 license: The GNU -GPL and The Artistic License (see the files README, Copying and +GPL and The Artistic License (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 simply state something like: +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 @@ -1160,8 +1244,8 @@ Remember to include the other words in addition to the Copyright. 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 valid floating point -number with at least two digits after the decimal (ie hundredths, +variable called $VERSION. This should be a floating point +number with at least two digits after the decimal (i.e., hundredths, e.g, C<$VERSION = "0.01">). Don't use a "1.3.2" style version. See Exporter.pm in Perl5.001m or later for details. @@ -1178,7 +1262,7 @@ 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 it's location in your announcement. +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 @@ -1195,10 +1279,10 @@ Follow the instructions and links on http://franz.ww.tu-berlin.de/modulelist -or upload to one of these sites: +or upload to one of these sites: ftp://franz.ww.tu-berlin.de/incoming - ftp://ftp.cis.ufl.edu/incoming + ftp://ftp.cis.ufl.edu/incoming and notify upload@franz.ww.tu-berlin.de. @@ -1289,8 +1373,7 @@ 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 +or perl -mModule::Name ... (in perl5.002) =back - |