=head1 NAME
-perlmod - Perl modules (packages)
+perlmod - Perl modules (packages and symbol tables)
=head1 DESCRIPTION
=head2 Packages
-Perl provides a mechanism for alternate namespaces to protect packages
-from stomping on each others variables. By default, a Perl script starts
-compiling into the package known as C<main>. You can switch namespaces
-using the C<package> declaration. The scope of the package declaration is
-from the declaration itself to the end of the enclosing block (the same
-scope as the local() operator). Typically it would be the first
-declaration in a file to be included by the C<require> operator. You can
-switch into a package in more than one place; it merely influences 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:
-C<$Package::Variable>. If the package name is null, the C<main> package
-as assumed. That is, C<$::sail> is equivalent to C<$main::sail>.
-
-(The old package delimiter was a single quote, but double colon
-is now the preferred delimiter, in part because it's more readable
-to humans, and in part because it's more readable to B<emacs> macros.
-It also makes C++ programmers feel like they know what's going on.)
+Perl provides a mechanism for alternative namespaces to protect packages
+from stomping on each other's variables. In fact, there's really no such
+thing as a global variable in Perl (although some identifiers default
+to the main package instead of the current one). The package statement
+declares the compilation unit as
+being in the given namespace. The scope of the package declaration
+is from the declaration itself through the end of the enclosing block,
+C<eval>, C<sub>, or end of file, whichever comes first (the same scope
+as the my() and local() operators). All further unqualified dynamic
+identifiers will be in this namespace. A package statement only affects
+dynamic variables--including those you've used local() on--but
+I<not> lexical variables created with my(). Typically it would be
+the first declaration in a file to be included by the C<require> or
+C<use> operator. You can switch into a package in more than one place;
+it merely influences which symbol table is used by the compiler for the
+rest of that block. You can refer to variables and filehandles in other
+packages by prefixing the identifier with the package name and a double
+colon: C<$Package::Variable>. If the package name is null, the C<main>
+package is assumed. That is, C<$::sail> is equivalent to C<$main::sail>.
+
+The old package delimiter was a single quote, but double colon is now the
+preferred delimiter, in part because it's more readable to humans, and
+in part because it's more readable to B<emacs> macros. It also makes C++
+programmers feel like they know what's going on--as opposed to using the
+single quote as separator, which was there to make Ada programmers feel
+like they knew what's going on. Because the old-fashioned syntax is still
+supported for backwards compatibility, if you try to use a string like
+C<"This is $owner's house">, you'll be accessing C<$owner::s>; that is,
+the $s variable in package C<owner>, which is probably not what you meant.
+Use braces to disambiguate, as in C<"This is ${owner}'s house">.
Packages may be nested inside other packages: C<$OUTER::INNER::var>. This
implies nothing about the order of name lookups, however. All symbols
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>.
-In addition, the identifiers STDIN, STDOUT, STDERR, C<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 since it will be interpreted instead
-as a pattern match, a substitution, or a translation.
+package's symbol table. All other symbols are kept in package C<main>,
+including all of the punctuation variables like $_. In addition, when
+unqualified, the identifiers STDIN, STDOUT, STDERR, ARGV, ARGVOUT, ENV,
+INC, and SIG are forced to be in package C<main>, even when used for other
+purposes than their builtin one. Note also that, if you have a package
+called C<m>, C<s>, or C<y>, then you can't use the qualified form of an
+identifier because it will be interpreted instead as a pattern match,
+a substitution, or a transliteration.
(Variables beginning with underscore used to be forced into package
main, but we decided it was more useful for package writers to be able
-to use leading underscore to indicate private variables and method names.)
+to use leading underscore to indicate private variables and method names.
+$_ is still global though.)
Eval()ed strings are compiled in the package in which the eval() was
compiled. (Assignments to C<$SIG{}>, however, assume the signal
-handler specified is in the C<main. package. Qualify the signal handler
+handler specified is in the C<main> package. Qualify the signal handler
name if you wish to have a signal handler in a package.) For an
example, examine F<perldb.pl> in the Perl library. It initially switches
to the C<DB> package so that the debugger doesn't interfere with variables
expressions in the context of the C<main> package (or wherever you came
from). See L<perldebug>.
+The special symbol C<__PACKAGE__> contains the current package, but cannot
+(easily) be used to construct variables.
+
+See L<perlsub> for other scoping issues related to my() and local(),
+and L<perlref> regarding closures.
+
=head2 Symbol Tables
-The symbol table for a package happens to be stored in the associative
-array of that name appended with two colons. The main symbol table's
-name is thus C<%main::>, or C<%::> for short. Likewise the nested package
-mentioned earlier is named C<%OUTER::INNER::>.
+The symbol table for a package happens to be stored in the hash of that
+name with two colons appended. The main symbol table's name is thus
+C<%main::>, or C<%::> for short. Likewise symbol table for the nested
+package mentioned earlier is named C<%OUTER::INNER::>.
-The value in each entry of the associative array is what you are
-referring to when you use the C<*name> notation. In fact, the following
-have the same effect, though the first is more efficient because it
-does the symbol table lookups at compile time:
+The value in each entry of the hash is what you are referring to when you
+use the C<*name> typeglob notation. In fact, the following have the same
+effect, though the first is more efficient because it does the symbol
+table lookups at compile time:
- local(*main::foo) = *main::bar; local($main::{'foo'}) =
- $main::{'bar'};
+ local *main::foo = *main::bar;
+ local $main::{foo} = $main::{bar};
You can use this to print out all the variables in a package, for
-instance. Here is F<dumpvar.pl> from the Perl library:
-
- package dumpvar;
- sub main::dumpvar {
- ($package) = @_;
- local(*stab) = eval("*${package}::");
- while (($key,$val) = each(%stab)) {
- local(*entry) = $val;
- if (defined $entry) {
- print "\$$key = '$entry'\n";
- }
-
- if (defined @entry) {
- print "\@$key = (\n";
- foreach $num ($[ .. $#entry) {
- print " $num\t'",$entry[$num],"'\n";
- }
- print ")\n";
- }
-
- if ($key ne "${package}::" && defined %entry) {
- print "\%$key = (\n";
- foreach $key (sort keys(%entry)) {
- print " $key\t'",$entry{$key},"'\n";
- }
- print ")\n";
- }
- }
- }
-
-Note that even though the subroutine is compiled in package C<dumpvar>,
-the name of the subroutine is qualified so that its name is inserted
-into package C<main>.
-
-Assignment to a symbol table entry performs an aliasing operation,
-i.e.,
+instance. The standard F<dumpvar.pl> library and the CPAN module
+Devel::Symdump make use of this.
+
+Assignment to a typeglob performs an aliasing operation, i.e.,
*dick = *richard;
-causes variables, subroutines and filehandles accessible via the
-identifier C<richard> to also be accessible via the symbol C<dick>. If
-you only want to alias a particular variable or subroutine, you can
-assign a reference instead:
+causes variables, subroutines, formats, and file and directory handles
+accessible via the identifier C<richard> also to be accessible via the
+identifier C<dick>. If you want to alias only a particular variable or
+subroutine, you can assign a reference instead:
*dick = \$richard;
-makes $richard and $dick the same variable, but leaves
+Which makes $richard and $dick the same variable, but leaves
@richard and @dick as separate arrays. Tricky, eh?
+This mechanism may be used to pass and return cheap references
+into or from subroutines if you won't want to copy the whole
+thing. It only works when assigning to dynamic variables, not
+lexicals.
+
+ %some_hash = (); # can't be my()
+ *some_hash = fn( \%another_hash );
+ sub fn {
+ local *hashsym = shift;
+ # now use %hashsym normally, and you
+ # will affect the caller's %another_hash
+ my %nhash = (); # do what you want
+ return \%nhash;
+ }
+
+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
+explicitly.
+
+Another use of symbol tables is for making "constant" scalars.
+
+ *PI = \3.14159265358979;
+
+Now you cannot alter $PI, which is probably a good thing all in all.
+This isn't the same as a constant subroutine, which is subject to
+optimization at compile-time. This isn't. A constant subroutine is one
+prototyped to take no arguments and to return a constant expression.
+See L<perlsub> for details on these. The C<use constant> pragma is a
+convenient shorthand for these.
+
+You can say C<*foo{PACKAGE}> and C<*foo{NAME}> to find out what name and
+package the *foo symbol table entry comes from. This may be useful
+in a subroutine that gets passed typeglobs as arguments:
+
+ sub identify_typeglob {
+ my $glob = shift;
+ print 'You gave me ', *{$glob}{PACKAGE}, '::', *{$glob}{NAME}, "\n";
+ }
+ identify_typeglob *foo;
+ identify_typeglob *bar::baz;
+
+This prints
+
+ You gave me main::foo
+ You gave me bar::baz
+
+The *foo{THING} notation can also be used to obtain references to the
+individual elements of *foo, see L<perlref>.
+
=head2 Package Constructors and Destructors
There are two special subroutine definitions that function as package
constructors and destructors. These are the C<BEGIN> and C<END>
routines. The C<sub> is optional for these routines.
-A C<BEGIN> subroutine is executed as soon as possible, that is, the
-moment it is completely defined, even before the rest of the containing
-file is parsed. You may have multiple C<BEGIN> blocks within a
-file--they will execute in order of definition. Because a C<BEGIN>
-block executes immediately, it can pull in definitions of subroutines
-and such from other files in time to be visible to the rest of the
-file.
-
-An C<END> subroutine is executed as late as possible, that is, when the
-interpreter is being exited, even if it is exiting as a result of a
-die() function. (But not if it's is being blown out of the water by a
-signal--you have to trap that yourself (if you can).) You may have
-multiple C<END> blocks within a file--they wil execute in reverse
-order of definition; that is: last in, first out (LIFO).
-
-Note that when you use the B<-n> and B<-p> switches to Perl, C<BEGIN>
-and C<END> work just as they do in B<awk>, as a degenerate case.
+A C<BEGIN> subroutine is executed as soon as possible, that is, the moment
+it is completely defined, even before the rest of the containing file
+is parsed. You may have multiple C<BEGIN> blocks within a file--they
+will execute in order of definition. Because a C<BEGIN> block executes
+immediately, it can pull in definitions of subroutines and such from other
+files in time to be visible to the rest of the file. Once a C<BEGIN>
+has run, it is immediately undefined and any code it used is returned to
+Perl's memory pool. This means you can't ever explicitly call a C<BEGIN>.
+
+An C<END> subroutine is executed as late as possible, that is, when
+the interpreter is being exited, even if it is exiting as a result of
+a die() function. (But not if it's polymorphing into another program
+via C<exec>, or being blown out of the water by a signal--you have to
+trap that yourself (if you can).) You may have multiple C<END> blocks
+within a file--they will execute in reverse 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 (e.g. by
+running something via C<system>).
+
+Note that when you use the B<-n> and B<-p> switches to Perl, C<BEGIN> and
+C<END> work just as they do in B<awk>, as a degenerate case. As currently
+implemented (and subject to change, since its inconvenient at best),
+both C<BEGIN> I<and> C<END> blocks are run when you use the B<-c> switch
+for a compile-only syntax check, although your main code is not.
=head2 Perl Classes
-There is no special class syntax in Perl 5, 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. For more on
-this, see L<perlobj>.
+There is no special class syntax in Perl, but a package may function
+as a class if it provides subroutines to act as methods. Such a
+package may also derive some of its methods from another class (package)
+by listing the other package name in its global @ISA array (which
+must be a package global, not a lexical).
+
+For more on this, see L<perltoot> and L<perlobj>.
=head2 Perl Modules
-In Perl 5, the notion of packages has been extended into the notion of
-modules. A module is a package that is defined in a library file of
+A module is just a package that is defined in a library file of
the same name, and is designed to be reusable. It may do this by
providing a mechanism for exporting some of its symbols into the symbol
table of any package using it. Or it may function as a class
calls on the class and its objects, without explicit exportation of any
symbols. Or it can do a little of both.
-Perl modules are included by saying
+For example, to start a normal module called Some::Module, create
+a file called Some/Module.pm and start with this template:
+
+ package Some::Module; # assumes Some/Module.pm
+
+ use strict;
+
+ BEGIN {
+ use Exporter ();
+ use vars qw($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
+
+ # set the version for version checking
+ $VERSION = 1.00;
+ # if using RCS/CVS, this may be preferred
+ $VERSION = do { my @r = (q$Revision: 2.21 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r }; # must be all one line, for MakeMaker
+
+ @ISA = qw(Exporter);
+ @EXPORT = qw(&func1 &func2 &func4);
+ %EXPORT_TAGS = ( ); # eg: TAG => [ qw!name1 name2! ],
+
+ # your exported package globals go here,
+ # as well as any optionally exported functions
+ @EXPORT_OK = qw($Var1 %Hashit &func3);
+ }
+ use vars @EXPORT_OK;
+
+ # non-exported package globals go here
+ use vars qw(@more $stuff);
+
+ # initalize package globals, first exported ones
+ $Var1 = '';
+ %Hashit = ();
+
+ # then the others (which are still accessible as $Some::Module::stuff)
+ $stuff = '';
+ @more = ();
+
+ # all file-scoped lexicals must be created before
+ # the functions below that use them.
+
+ # file-private lexicals go here
+ my $priv_var = '';
+ my %secret_hash = ();
+
+ # here's a file-private function as a closure,
+ # callable as &$priv_func; it cannot be prototyped.
+ my $priv_func = sub {
+ # stuff goes here.
+ };
+
+ # make all your functions, whether exported or not;
+ # remember to put something interesting in the {} stubs
+ sub func1 {} # no prototype
+ sub func2() {} # proto'd void
+ sub func3($$) {} # proto'd to 2 scalars
+
+ # this one isn't exported, but could be called!
+ sub func4(\%) {} # proto'd to 1 hash ref
+
+ END { } # module clean-up code here (global destructor)
+
+Then go on to declare and use your variables in functions
+without any qualifications.
+See L<Exporter> and the L<perlmodlib> for details on
+mechanics and style issues in module creation.
+
+Perl modules are included into your program by saying
use Module;
This is exactly equivalent to
- BEGIN { require "Module.pm"; import Module; }
+ BEGIN { require Module; import Module; }
or
- BEGIN { require "Module.pm"; import Module LIST; }
+ BEGIN { require Module; import Module LIST; }
+
+As a special case
+
+ use Module ();
+
+is exactly equivalent to
+
+ BEGIN { require Module; }
All Perl module files have the extension F<.pm>. C<use> assumes this so
that you don't have to spell out "F<Module.pm>" in quotes. This also
"Pragmas" are in effect compiler directives, and are sometimes called
"pragmatic modules" (or even "pragmata" if you're a classicist).
+The two statements:
+
+ require SomeModule;
+ require "SomeModule.pm";
+
+differ from each other in two ways. In the first case, any double
+colons in the module name, such as C<Some::Module>, are translated
+into your system's directory separator, usually "/". The second
+case does not, and would have to be specified literally. The other difference
+is that seeing the first C<require> clues in the compiler that uses of
+indirect object notation involving "SomeModule", as in C<$ob = purge SomeModule>,
+are method calls, not function calls. (Yes, this really can make a difference.)
+
Because the C<use> statement implies a C<BEGIN> block, the importation
of semantics happens at the moment the C<use> statement is compiled,
before the rest of the file is compiled. This is how it is able
to function as a pragma mechanism, and also how modules are able to
declare subroutines that are then visible as list operators for
the rest of the current file. This will not work if you use C<require>
-instead of C<use>. Therefore, if you're planning on the module altering
-your namespace, use C<use>; otherwise, use C<require>. Otherwise you
-can get into this problem:
+instead of C<use>. With require you can get into this problem:
require Cwd; # make Cwd:: accessible
- $here = Cwd::getcwd();
+ $here = Cwd::getcwd();
- use Cwd; # import names from Cwd::
+ use Cwd; # import names from Cwd::
$here = getcwd();
require Cwd; # make Cwd:: accessible
$here = getcwd(); # oops! no main::getcwd()
+In general, C<use Module ()> is recommended over C<require Module>,
+because it determines module availability at compile time, not in the
+middle of your program's execution. An exception would be if two modules
+each tried to C<use> each other, and each also called a function from
+that other module. In that case, it's easy to use C<require>s instead.
+
Perl packages may be nested inside other package names, so we can have
package names containing C<::>. But if we used that package name
directly as a filename it would makes for unwieldy or impossible
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<perlapi>
+For more information on writing extension modules, see L<perlxstut>
and L<perlguts>.
-=head1 NOTE
-
-Perl does not enforce private and public parts of its modules as you may
-have been used to in other languages like C++, Ada, or Modula-17. Perl
-doesn't have an infatuation with enforced privacy. It would prefer
-that you stayed out of its living room because you weren't invited, not
-because it has a shotgun.
-
-The module and its user have a contract, part of which is common law,
-and part of which is "written". Part of the common law contract is
-that a module doesn't pollute any namespace it wasn't asked to. The
-written contract for the module (AKA 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
-the library directory that end in either F<.pl> or F<.ph>. These are old
-libaries supplied so that old programs that use them still run. The
-F<.pl> files will all eventually be converted into standard modules, and
-the F<.ph> files made by B<h2ph> will probably end up as extension modules
-made by B<h2xs>. (Some F<.ph> values may already be available through the
-POSIX module.) The B<pl2pm> file in the distribution may help in your
-conversion, but it's just a mechanical process, so is far from bullet proof.
-
-=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
-C<use>, or C<no>. These are locally scoped, so if an inner BLOCK
-may countermand any of these by saying
-
- no integer;
- no strict 'refs';
-
-which lasts until the end of that BLOCK.
-
-The following programs are defined (and have their own documentation).
-
-=over 12
-
-=item C<integer>
-
-Perl pragma to compute arithmetic in integer instead of double
-
-=item C<less>
-
-Perl pragma to request less of something from the compiler
-
-=item C<sigtrap>
-
-Perl pragma to enable stack backtrace on unexpected signals
-
-=item C<strict>
-
-Perl pragma to restrict unsafe constructs
-
-=item C<subs>
-
-Perl pragma to predeclare sub names
-
-=back
-
-=head2 Standard Modules
-
-The following modules are all expacted to behave in a well-defined
-manner with respect to namespace pollution because they use the
-Exporter module.
-See their own documentation for details.
-
-=over 12
-
-=item C<Abbrev>
-
-create an abbreviation table from a list
-
-=item C<AnyDBM_File>
-
-provide framework for multiple DBMs
-
-=item C<AutoLoader>
-
-load functions only on demand
-
-=item C<AutoSplit>
-
-split a package for autoloading
-
-=item C<Basename>
-
-parse file anme and path from a specification
-
-=item C<Benchmark>
-
-benchmark running times of code
-
-=item C<Carp>
-
-warn or die of errors (from perspective of caller)
-
-=item C<CheckTree>
-
-run many filetest checks on a tree
-
-=item C<Collate>
-
-compare 8-bit scalar data according to the current locale
-
-=item C<Config>
-
-access Perl configuration option
-
-=item C<Cwd>
-
-get pathname of current working directory
-
-=item C<DynaLoader>
-
-Dynamically load C libraries into Perl code
-
-=item C<English>
-
-use nice English (or B<awk>) names for ugly punctuation variables
-
-=item C<Env>
-
-Perl module that imports environment variables
-
-=item C<Exporter>
-
-module to control namespace manipulations
-
-=item C<Fcntl>
-
-load the C Fcntl.h defines
-
-=item C<FileHandle>
-
-supply object methods for filehandles
-
-=item C<Find>
-
-traverse a file tree
-
-=item C<Finddepth>
-
-traverse a directory structure depth-first
-
-=item C<Getopt>
-
-basic and extended getopt(3) processing
-
-=item C<MakeMaker>
-
-generate a Makefile for Perl extension
-
-=item C<Open2>
-
-open a process for both reading and writing
-
-=item C<Open3>
-
-open a process for reading, writing, and error handling
-
-=item C<POSIX>
-
-Perl interface to IEEE 1003.1 namespace
-
-=item C<Ping>
-
-check a host for upness
-
-=item C<Socket>
-
-load the C socket.h defines
-
-=back
-
-=head2 Extension Modules
-
-Extension modules are written in C (or a mix of Perl and C) and get
-dynamically loaded into Perl if and when you need them. Supported
-extension modules include the Socket, Fcntl, and POSIX modules.
-
-The following are popular C extension modules, which while available at
-Perl 5.0 release time, do not come not bundled (at least, not completely)
-due to their size, 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 their authors before randomly
-posting asking for their present condition and disposition. There's no
-guarantee that the names or addresses below have not changed since printing,
-and in fact, they probably have!
-
-=over 12
-
-=item C<Curses>
-
-Written by William Setzer <F<William_Setzer@ncsu.edu>>, while not
-included with the standard distribution, this extension module ports to
-most systems. FTP from your nearest Perl archive site, or try
-
- ftp://ftp.ncsu.edu/pub/math/wsetzer/cursperl5??.tar.gz
-
-It is currently in alpha test, so the name and ftp location may
-change.
-
-
-=item C<DBI>
-
-This is the portable database interface written by
-<F<Tim.Bunce@ig.co.uk>>. This supersedes the many perl4 ports for
-database extensions. The official archive for DBperl extensions is
-F<ftp.demon.co.uk:/pub/perl/db>. This archive contains copies of perl4
-ports for Ingres, Oracle, Sybase, Informix, Unify, Postgres, and
-Interbase, as well as rdb and shql and other non-SQL systems.
-
-=item C<DB_File>
-
-Fastest and most restriction-free of the DBM bindings, this extension module
-uses the popular Berkeley DB to tie() into your hashes. This has a
-standardly-distributed man page and dynamic loading extension module, but
-you'll have to fetch the Berkeley code yourself. See L<DB_File> for
-where.
-
-=item C<Sx>
-
-This extension module is a front to the Athena and Xlib libraries for Perl
-GUI progamming, originally written by by Dominic Giampaolo
-<F<dbg@sgi.com>>, then and rewritten for Sx by FrE<eacute>dE<eacute>ric
-Chauveau <F<fmc@pasteur.fr>>. It's available for FTP from
-
- ftp.pasteur.fr:/pub/Perl/Sx.tar.gz
-
-=item C<Tk>
-
-This extension module is an object-oriented Perl5 binding to the popular
-tcl/tk X11 package. However, you need know no TCL to use it!
-It was written by Malcolm Beattie <F<mbeattie@sable.ox.ac.uk>>.
-If you are unable to locate it using archie(1L) or a similar
-tool, you may try retrieving it from F</private/Tk-october.tar.gz>
-from Malcolm's machine listed above.
+=head1 SEE ALSO
-=back
+See L<perlmodlib> for general style issues related to building Perl
+modules and classes as well as descriptions of the standard library and
+CPAN, L<Exporter> for how Perl's standard import/export mechanism works,
+L<perltoot> for an in-depth tutorial on creating classes, L<perlobj>
+for a hard-core reference document on objects, and L<perlsub> for an
+explanation of functions and scoping.
https://perl5.git.perl.org / perl5.git / blobdiff