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.
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
*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 want to alias only a particular variable or subroutine, you can
assign a reference instead:
# 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 will overwrite the hash slot in the
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>.
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
require Cwd; # make Cwd:: accessible
$here = Cwd::getcwd();
- use Cwd; # import names from Cwd::
+ use Cwd; # import names from Cwd::
$here = getcwd();
require Cwd; # make Cwd:: accessible
=head1 THE PERL MODULE LIBRARY
A number of modules are included the Perl distribution. These are
-described below, and all end in F<.pm>. You may also discover files in
+described below, and all end in F<.pm>. You may also discover files in
the library directory that end in either F<.pl> or F<.ph>. These are old
libraries supplied so that old programs that use them still run. The
F<.pl> files will all eventually be converted into standard modules, and
the F<.ph> files made by B<h2ph> will probably end up as extension modules
made by B<h2xs>. (Some F<.ph> values may already be available through the
POSIX module.) The B<pl2pm> file in the distribution may help in your
-conversion, but it's just a mechanical process, so is far from bulletproof.
+conversion, but it's just a mechanical process and therefore far from
+bulletproof.
=head2 Pragmatic Modules
Unlike the pragmas that effect the C<$^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
+I<file> rather than just a block. Such declarations are effective
for the entire file for which they were declared. You cannot rescind
them with C<no vars> or C<no subs>.
=over 12
+=item blib
+
+manipulate @INC at compile time to use MakeMaker's uninstalled version
+of a package
+
=item diagnostics
force verbose warning diagnostics
manipulate @INC at compile time
+=item locale
+
+use or ignore current locale for built-in operations (see L<perllocale>)
+
=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
pre-declare sub names
+=item vmsish
+
+adopt certain VMS-specific behaviors
+
=item vars
pre-declare global variable names
benchmark running times of code
+=item CPAN
+
+interface to Comprehensive Perl Archive Network
+
+=item CPAN::FirstTime
+
+create a CPAN configuration file
+
+=item CPAN::Nox
+
+run CPAN while avoiding compiled extensions
+
=item Carp
warn of errors (from perspective of caller)
+=item Class::Template
+
+struct/member template builder
+
=item Config
access Perl configuration information
=item DynaLoader
-Dynamically load C libraries into Perl code
+dynamically load C libraries into Perl code
=item English
=item ExtUtils::Embed
-Utilities for embedding Perl in C/C++ applications
+utilities for embedding Perl in C/C++ applications
=item ExtUtils::Install
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
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
write linker options files for dynamic extension
-=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::testlib
add blib/* directories to @INC
-=item Fatal
-
-replace functions with equivalents which succeed or die
-
=item Fcntl
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
=item Net::Ping
-check a host for upness
+Hello, anybody home?
+
+=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
=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
=item Term::Cap
-Perl termcap interface
+termcap interface
=item Term::Complete
=item Term::ReadLine
-interface to various readline packages.
+interface to various C<readline> packages
=item Test::Harness
=item Text::Soundex
-implementation of the Soundex Algorithm as Described by Knuth
+implementation of the Soundex Algorithm as described by Knuth
=item Text::Tabs
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
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
=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
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
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
=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
into the class name given as the first parameter of the constructor,
e.g.,:
- sub new {
+ sub new {
my $class = shift;
return bless {}, $class;
}
or even this if you'd like it to be used as either a static
or a virtual method.
- sub new {
+ sub new {
my $self = shift;
my $class = ref($self) || $self;
return bless {}, $class;
=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
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
+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.
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
+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.
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.
the application could invoked as:
perl -e 'use Module::Name; method(@ARGV)' ...
-or
+or
perl -mModule::Name ... (in perl5.002)
=back
-
projects / p5sagit/p5-mst-13.2.git / blobdiff