Standard Modules (Perl in a Nutshell, 2nd Edition)

We've talked about the extent to which Perl benefits from user contributions. In fact, many contributed modules are so generally useful that they are now distributed with Perl itself. This chapter describes these "standard modules"; if you are running Perl 5.005, all these modules are already available to you. If you are running an earlier version of Perl, and you find that a module you want isn't on your system, or if you simply don't find what you need among the modules in this chapter, check CPAN for one that does what you want.

While this chapter primarily covers standard Perl modules called at execution time from your program, it also covers the "pragmatic" modules that affect the compilation phase. (A pragma is a compiler directive that provides hints to the compiler.) By convention, the names of the pragmatic modules are all lowercase, while the names of other modules begin with an uppercase letter and are of mixed case.

The following table provides a quick look at the standard modules and what they do:

Module	Function
AnyDBM_File	Provides framework for multiple DBMs
Attribute::Handlers	Simpler definition of attribute handlers (new in 5.8)
attributes	Sets or gets attributes of a subroutine
attrs	Sets or gets attributes of a subroutine (deprecated)
AutoLoader	Loads functions only on demand
AutoSplit	Splits a module for autoloading
autouse	Postpones loading modules until a function is used
B	Perl compiler and tools
base	Establishes IS-A relationship with base class at compile time
Benchmark	Checks and compares running times of code
bigint	Transparent big integer support for Perl (new in 5.8)
bignum	Transparent BigNumber support for Perl (new in 5.8)
bigrat	Transparent BigNumber/BigRational support for Perl (new in 5.8)
blib	Uses MakeMaker's uninstalled version of a package
bytes	Perl pragma to force byte semantics rather than character semantics
ByteLoader	Loads byte-compiled Perl code
Carp	Generates error messages
CGI	Simple Common Gateway Interface class
CGI::Apache	Sets up environment to use CGI with Perl-Apache API
CGI::Carp	CGI routines for writing to HTTPD (or other) error log
CGI::Cookie	CGI interface to Netscape (HTTP/1.1) cookies
CGI::Fast	CGI interface for FastCGI
CGI::Pretty	Module to produce nicely formatted HTML code
CGI::Push	Interface for server push operations
CGI::Switch	Tries multiple constructors and returns the first available CGI object
charnames	Defines character names for `\N{named}` string literal escape
Class::ISA	Reports the search path for a class's ISA tree (new in 5.8)
Class::Struct	Declares struct-like datatypes as Perl classes
Config	Accesses Perl configuration information
constant	Perl pragma to declare constants
CPAN	Queries, downloads, and builds Perl modules from CPAN sites
CPAN::FirstTime	Utility for CPAN::Config file initialization
CPAN::Nox	Wrapper around CPAN.pm without using any XS module
Cwd	Gets pathname of current working directory
Data::Dumper	Returns Perl data structures as strings
DB	Programmatic interface to the Perl debugging API
DB_File	Accesses Berkeley DB
Devel::DProf	Perl Code Profiler
Devel::PPPort	Module that assists with module porting between Perl versions
Devel::SelfStubber	Generates stubs for a self-loading module
diagnostics	Forces verbose warning diagnostics
Digest	Modules that calculate message digests (new in 5.8)
Digest::MD5	Perl interface to the MD5 Algorithm (new in 5.8)
DirHandle	Supplies object methods for directory handles
Dumpvalue	Provides a screen dump of Perl data
DynaLoader	Automatic dynamic loading of Perl modules
encoding	Allows you to write your script in nonasii or nonutf8 (new in 5.8)
English	Uses English or awk names for punctuation variables
Env	Imports environment variables
Errno	System errno constants from errno.h include file
Exporter	Default import method for modules
ExtUtils::Command	Utilities to replace common Unix commands
ExtUtils::Command::MM	Commands that the MM's can use in Makefiles (new in 5.8)
ExtUtils::Constant	Generates XS code to import C header constants (new in 5.8)
ExtUtils::Embed	Utilities for embedding Perl in C/C++ applications
ExtUtils::Install	Installs files from here to there
ExtUtils::Installed	Inventory management of installed modules
ExtUtils::Liblist	Determines libraries to use and how to use them
ExtUtils::MakeMaker	Creates a Makefile for a Perl extension
ExtUtils::Manifest	Utilities to write and check a MANIFEST file
ExtUtils::Miniperl	Writes the C code for perlmain.c
ExtUtils::Mkbootstrap	Makes a bootstrap file for use by DynaLoader
ExtUtils::Mksymlists	Writes linker option files for dynamic extension
ExtUtils::MM	Operating system-adjusted ExtUtils::MakeMaker subclass (new in 5.8)
ExtUtils::MM_Any	Platform-agnostic MM methods (new in 5.8)
ExtUtils::MM_BeOS	Methods that override UN*X behavior in ExtUtils::MakeMaker (new in 5.8)
ExtUtils::MM_DOS	DOS-specific subclass of ExtUtils::MM_Unix (new in 5.8)
ExtUtils::MM_NW5	Methods that override UN*X behavior in ExtUtils::MakeMaker (new in 5.8)
ExtUtils::MM_OS2	Methods to override Unix behavior in ExtUtils::MakeMaker
ExtUtils::MM_Unix	Methods used by ExtUtils::MakeMaker
ExtUtils::MM_UWIN	U/WIN-specific subclass of ExtUtils::MM_Unix (new in 5.8)
ExtUtils::MM_VMS	Methods to override Unix behavior in ExtUtils::MakeMaker
ExtUtils::MM_Win32	Methods to override Unix behavior in ExtUtils::MakeMaker
ExtUtils::MY	ExtUtils::MakeMaker subclass for customization (new in 5.8)
ExtUtils::Packlist	Manages .packlist files
ExtUtils::testlib	Adds blib/* directories to `@INC`
Fatal	Replaces functions with equivalents that succeed or die
Fcntl	Loads the C fcntl.h defines
fields	Perl pragma to provide compile time-verified class fields
File::Basename	Parses file specifications
File::CheckTree	Runs many tests on a collection of files
File::Compare	Compares files or filehandles
File::Copy	Copies files or filehandles
File::DosGlob	DOS-like globbing with enhancements
File::Find	Traverses a file tree
File::Path	Creates or removes a series of directories
File::Spec	Portably performs operations on filenames
File::Spec::Cygwin	Methods for Cygwin file specs (new in 5.8)
File::stat	By-name interface to Perl's built-in `stat` functions
File::Temp	Returns the name and handle of a temporary file safely
FileCache	Keeps more files open than the system permits
FileHandle	Supplies object methods for filehandles
Filter::Simple	Simplified source filtering (new in 5.8)
Filter::Util::Call	Perl Source Filter Utility Module (new in 5.8)
FindBin	Locates directory of original Perl script
GDBM_File	Tied access to GDBM library
Getopt::Long	Extended processing of command-line options
Getopt::Std	Processes single-character options with option clustering
Hash::Util	A selection of general utility hash subroutines (new in 5.8)
I18N::Collate	Compares 8-bit scalar data according to the current locale
I18N::Langinfo	Queries locale information (new in 5.8)
I18N::LangTags	Functions for dealing with RFC3066-style language tags (new in 5.8)
I18N::LangTags::List	Tags and names for human languages (new in 5.8)
if	Uses a Perl module if a condition holds (new in 5.8)
integer	Does arithmetic in integer instead of double
IO	Loads various I/O modules
IO::File	Supplies object methods for filehandles
IO::Handle	Supplies object methods for I/O handles
IO::Pipe	Supplies object methods for pipes
IO::Seekable	Supplies seek-based methods for I/O objects
IO::Select	Object-oriented interface to the select system call
IO::Socket	Object interface to socket communications
IPC::Msg	System V Msg IPC object class
IPC::Open2	Opens a process for both reading and writing
IPC::Open3	Opens a process for reading, writing, and error handling
IPC::Semaphore	System V Semaphore IPC object class
IPC::SysV	System V IPC constants
less	Perl pragma to request less of something from the compiler
lib	Manipulates `@INC` at compile time
List::Util	A selection of general utility list subroutines (new in 5.8)
locale	Perl pragma to use and avoid POSIX locales for built-in operations
Math::BigFloat	Arbitrary-length floating-point math package
Math::BigInt	Arbitrary-length integer math package
Math::BigInt::Calc	Pure Perl module to support Math::BigInt (new in 5.8)
Math::BigRat	Arbitrarily big rationals (new in 5.8)
Math::Complex	Complex numbers package
Math::Trig	Trigonometric functions
MIME::Base64	Encoding and decoding of base64 strings (new in 5.8)
MIME::QuotedPrint	Encoding and decoding of quoted, printable strings (new in 5.8)
NDBM_File	Tied access to NDBM files
Net::Cmd	Network Command class (new in 5.8)
Net::Config	Local configuration data for libnet (new in 5.8)
Net::Domain	Attempts to evaluate the current host's Internet name and domain (new in 5.8)
Net::FTP	FTP Client class (new in 5.8)
Net::hostent	By-name interface to Perl's built-in `gethost*` functions
Net::netent	By-name interface to Perl's built-in `getnet*` functions
Net::Netrc	OO interface to user's netrc file (new in 5.8)
Net::NNTP	NNTP Client class (new in 5.8)
Net::Ping	Checks whether a host is online
Net::POP3	Post Office Protocol 3 Client class (new in 5.8)
Net::protoent	By-name interface to Perl's built-in `getproto*` functions
Net::servent	By-name interface to Perl's built-in `getserv*` functions
Net::SMTP	Simple Mail Transfer Protocol Client class (new in 5.8)
Net::Time	Time and daytime network client interface (new in 5.8)
ODBM_File	Tied access to ODBM files
Opcode	Disables named opcodes when compiling Perl code
ops	Restricts unsafe operations when compiling
overload	Overloads Perl's mathematical operations
PerlIO	On-demand loader for PerlIO layers and root of PerlIO::* namespace (added in 5.8)
PerlIO::Scalar	Support module for in-memory I/O (new in 5.8)
PerlIO::Via	Helper class for PerlIO layers implemented in Perl (new in 5.8)
Pod::Functions	Used in converting from pod to HTML
Pod::Html	Module to convert pod files to HTML
Pod::ParseLink	Parses link-formatting code in POD documents (new in 5.8)
Pod::Text	Converts pod data to formatted ASCII text
POSIX	Perl interface to IEEE Std 1003.1
re	Perl pragma to alter regular expression behavior
Safe	Creates safe namespaces for evaluating Perl code
Scalar::Util	A selection of general-utility scalar subroutines (new in 5.8)
SDBM_File	Tied access to SDBM files
Search::Dict	Searches for key in dictionary file
SelectSaver	Saves and restores selected filehandle
SelfLoader	Loads functions only on demand
Shell	Runs shell commands transparently within Perl
sigtrap	Enables stack backtrace on unexpected signals
Socket	Loads the C socket.h defines and structure manipulators
sort	Perl pragma that controls sort behavior (new in 5.8)
Storable	Persistence for Perl data structures (new in 5.8)
strict	Restricts unsafe constructs
subs	Predeclares subroutine names
Switch	A switch statement for Perl (new in 5.8)
Symbol	Generates anonymous globs; qualifies variable names
Sys::Hostname	Tries every conceivable way to get hostname
Sys::Syslog	Perl interface to Unix `syslog(3)` calls
Term::Cap	Terminal capabilities interface
Term::Complete	Word completion module
Term::ReadLine	Interface to various ReadLine packages
Test	Framework for writing test scripts
Test::Builder	Backend for building text libraries (new in 5.8)
Test::Harness	Runs Perl standard test scripts with statistics
Test::More	Yet another framework for writing test scripts (new in 5.8)
Test::Simple	Basic utilities for writing tests (new in 5.8)
Text::Abbrev	Creates an abbreviation table from a list
Text::Balanced	Extracts delimited text sequences from strings (new in 5.8)
Text::ParseWords	Parses text into a list of tokens
Text::Soundex	The soundex algorithm described by Knuth
Text::Tabs	Expands and unexpands tabs
Text::Wrap	Wraps text into a paragraph
Thread	Multithreading support
Thread::Queue	Thread-safe queues
Thread::Semaphore	Thread-safe semaphores
Thread::Signal	Starts a thread that runs signal handlers reliably
Thread::Specific	Thread-specific keys
Tie::Array	Base class definitions for tied arrays
Tie::File	Accesses the lines of a disk file via a Perl array (new in 5.8)
Tie::Handle	Base class definitions for tied handles
Tie::Hash	Base class definitions for tied hashes
Tie::Memorize	Adds data to a hash when needed (new in 5.8)
Tie::RefHash	Uses references as hash keys
Tie::Scalar	Base class definitions for tied scalars
Tie::SubstrHash	Fixed table size, fixed key length hashing
Time::gmtime	By-name interface to Perl's built-in `gmtime` function
Time::HiRes	High-resolution alarm, sleep, gettimeofday, interval timers (new in 5.8)
Time::Local	Computes time from local and GMT time
Time::localtime	By-name interface to Perl's built-in `localtime` function
Time::tm	Internal object used by Time::gmtime and Time::localtime
UNIVERSAL	Base class for all classes (blessed references)
User::grent	By-name interface to Perl's built-in `getgr*` functions
User::pwent	By-name interface to Perl's built-in `getpw*` functions
utf8	Perl pragma to enable/disable UTF-8 in source code
vars	Predeclares global variable names
vmsish	Perl pragma that controls VMS-specific language features (new in 5.8)
XS::Typemap	Module that tests the XS typemaps distributed with Perl (new in 5.8)

Module

Function

AnyDBM_File

Provides framework for multiple DBMs

Attribute::Handlers

Simpler definition of attribute handlers (new in 5.8)

attributes

Sets or gets attributes of a subroutine

attrs

Sets or gets attributes of a subroutine (deprecated)

AutoLoader

Loads functions only on demand

AutoSplit

Splits a module for autoloading

autouse

Postpones loading modules until a function is used

Perl compiler and tools

base

Establishes IS-A relationship with base class at compile time

Benchmark

Checks and compares running times of code

bigint

Transparent big integer support for Perl (new in 5.8)

bignum

Transparent BigNumber support for Perl (new in 5.8)

bigrat

Transparent BigNumber/BigRational support for Perl (new in 5.8)

blib

Uses MakeMaker's uninstalled version of a package

bytes

Perl pragma to force byte semantics rather than character semantics

ByteLoader

Loads byte-compiled Perl code

Carp

Generates error messages

CGI

Simple Common Gateway Interface class

CGI::Apache

Sets up environment to use CGI with Perl-Apache API

CGI::Carp

CGI routines for writing to HTTPD (or other) error log

CGI::Cookie

CGI interface to Netscape (HTTP/1.1) cookies

CGI::Fast

CGI interface for FastCGI

CGI::Pretty

Module to produce nicely formatted HTML code

CGI::Push

Interface for server push operations

CGI::Switch

Tries multiple constructors and returns the first available CGI object

charnames

Defines character names for \N{named} string literal escape

Class::ISA

Reports the search path for a class's ISA tree (new in 5.8)

Class::Struct

Declares struct-like datatypes as Perl classes

Config

Accesses Perl configuration information

constant

Perl pragma to declare constants

CPAN

Queries, downloads, and builds Perl modules from CPAN sites

CPAN::FirstTime

Utility for CPAN::Config file initialization

CPAN::Nox

Wrapper around CPAN.pm without using any XS module

Cwd

Gets pathname of current working directory

Data::Dumper

Returns Perl data structures as strings

Programmatic interface to the Perl debugging API

DB_File

Accesses Berkeley DB

Devel::DProf

Perl Code Profiler

Devel::PPPort

Module that assists with module porting between Perl versions

Devel::SelfStubber

Generates stubs for a self-loading module

diagnostics

Forces verbose warning diagnostics

Digest

Modules that calculate message digests (new in 5.8)

Digest::MD5

Perl interface to the MD5 Algorithm (new in 5.8)

DirHandle

Supplies object methods for directory handles

Dumpvalue

Provides a screen dump of Perl data

DynaLoader

Automatic dynamic loading of Perl modules

encoding

Allows you to write your script in nonasii or nonutf8 (new in 5.8)

English

Uses English or awk names for punctuation variables

Env

Imports environment variables

Errno

System errno constants from errno.h include file

Exporter

Default import method for modules

ExtUtils::Command

Utilities to replace common Unix commands

ExtUtils::Command::MM

Commands that the MM's can use in Makefiles (new in 5.8)

ExtUtils::Constant

Generates XS code to import C header constants (new in 5.8)

ExtUtils::Embed

Utilities for embedding Perl in C/C++ applications

ExtUtils::Install

Installs files from here to there

ExtUtils::Installed

Inventory management of installed modules

ExtUtils::Liblist

Determines libraries to use and how to use them

ExtUtils::MakeMaker

Creates a Makefile for a Perl extension

ExtUtils::Manifest

Utilities to write and check a MANIFEST file

ExtUtils::Miniperl

Writes the C code for perlmain.c

ExtUtils::Mkbootstrap

Makes a bootstrap file for use by DynaLoader

ExtUtils::Mksymlists

Writes linker option files for dynamic extension

ExtUtils::MM

Operating system-adjusted ExtUtils::MakeMaker subclass (new in 5.8)

ExtUtils::MM_Any

Platform-agnostic MM methods (new in 5.8)

ExtUtils::MM_BeOS

Methods that override UN*X behavior in ExtUtils::MakeMaker (new in 5.8)

ExtUtils::MM_DOS

DOS-specific subclass of ExtUtils::MM_Unix (new in 5.8)

ExtUtils::MM_NW5

Methods that override UN*X behavior in ExtUtils::MakeMaker (new in 5.8)

ExtUtils::MM_OS2

Methods to override Unix behavior in ExtUtils::MakeMaker

ExtUtils::MM_Unix

Methods used by ExtUtils::MakeMaker

ExtUtils::MM_UWIN

U/WIN-specific subclass of ExtUtils::MM_Unix (new in 5.8)

ExtUtils::MM_VMS

Methods to override Unix behavior in ExtUtils::MakeMaker

ExtUtils::MM_Win32

Methods to override Unix behavior in ExtUtils::MakeMaker

ExtUtils::MY

ExtUtils::MakeMaker subclass for customization (new in 5.8)

ExtUtils::Packlist

Manages .packlist files

ExtUtils::testlib

Adds blib/* directories to @INC

Fatal

Replaces functions with equivalents that succeed or die

Fcntl

Loads the C fcntl.h defines

fields

Perl pragma to provide compile time-verified class fields

File::Basename

Parses file specifications

File::CheckTree

Runs many tests on a collection of files

File::Compare

Compares files or filehandles

File::Copy

Copies files or filehandles

File::DosGlob

DOS-like globbing with enhancements

File::Find

Traverses a file tree

File::Path

Creates or removes a series of directories

File::Spec

Portably performs operations on filenames

File::Spec::Cygwin

Methods for Cygwin file specs (new in 5.8)

File::stat

By-name interface to Perl's built-in stat functions

File::Temp

Returns the name and handle of a temporary file safely

FileCache

Keeps more files open than the system permits

FileHandle

Supplies object methods for filehandles

Filter::Simple

Simplified source filtering (new in 5.8)

Filter::Util::Call

Perl Source Filter Utility Module (new in 5.8)

FindBin

Locates directory of original Perl script

GDBM_File

Tied access to GDBM library

Getopt::Long

Extended processing of command-line options

Getopt::Std

Processes single-character options with option clustering

Hash::Util

A selection of general utility hash subroutines (new in 5.8)

I18N::Collate

Compares 8-bit scalar data according to the current locale

I18N::Langinfo

Queries locale information (new in 5.8)

I18N::LangTags

Functions for dealing with RFC3066-style language tags (new in 5.8)

I18N::LangTags::List

Tags and names for human languages (new in 5.8)

Uses a Perl module if a condition holds (new in 5.8)

integer

Does arithmetic in integer instead of double

Loads various I/O modules

IO::File

Supplies object methods for filehandles

IO::Handle

Supplies object methods for I/O handles

IO::Pipe

Supplies object methods for pipes

IO::Seekable

Supplies seek-based methods for I/O objects

IO::Select

Object-oriented interface to the select system call

IO::Socket

Object interface to socket communications

IPC::Msg

System V Msg IPC object class

IPC::Open2

Opens a process for both reading and writing

IPC::Open3

Opens a process for reading, writing, and error handling

IPC::Semaphore

System V Semaphore IPC object class

IPC::SysV

System V IPC constants

less

Perl pragma to request less of something from the compiler

lib

Manipulates @INC at compile time

List::Util

A selection of general utility list subroutines (new in 5.8)

locale

Perl pragma to use and avoid POSIX locales for built-in operations

Math::BigFloat

Arbitrary-length floating-point math package

Math::BigInt

Arbitrary-length integer math package

Math::BigInt::Calc

Pure Perl module to support Math::BigInt (new in 5.8)

Math::BigRat

Arbitrarily big rationals (new in 5.8)

Math::Complex

Complex numbers package

Math::Trig

Trigonometric functions

MIME::Base64

Encoding and decoding of base64 strings (new in 5.8)

MIME::QuotedPrint

Encoding and decoding of quoted, printable strings (new in 5.8)

NDBM_File

Tied access to NDBM files

Net::Cmd

Network Command class (new in 5.8)

Net::Config

Local configuration data for libnet (new in 5.8)

Net::Domain

Attempts to evaluate the current host's Internet name and domain (new in 5.8)

Net::FTP

FTP Client class (new in 5.8)

Net::hostent

By-name interface to Perl's built-in gethost* functions

Net::netent

By-name interface to Perl's built-in getnet* functions

Net::Netrc

OO interface to user's netrc file (new in 5.8)

Net::NNTP

NNTP Client class (new in 5.8)

Net::Ping

Checks whether a host is online

Net::POP3

Post Office Protocol 3 Client class (new in 5.8)

Net::protoent

By-name interface to Perl's built-in getproto* functions

Net::servent

By-name interface to Perl's built-in getserv* functions

Net::SMTP

Simple Mail Transfer Protocol Client class (new in 5.8)

Net::Time

Time and daytime network client interface (new in 5.8)

ODBM_File

Tied access to ODBM files

Opcode

Disables named opcodes when compiling Perl code

ops

Restricts unsafe operations when compiling

overload

Overloads Perl's mathematical operations

PerlIO

On-demand loader for PerlIO layers and root of PerlIO::* namespace (added in 5.8)

PerlIO::Scalar

Support module for in-memory I/O (new in 5.8)

PerlIO::Via

Helper class for PerlIO layers implemented in Perl (new in 5.8)

Pod::Functions

Used in converting from pod to HTML

Pod::Html

Module to convert pod files to HTML

Pod::ParseLink

Parses link-formatting code in POD documents (new in 5.8)

Pod::Text

Converts pod data to formatted ASCII text

POSIX

Perl interface to IEEE Std 1003.1

Perl pragma to alter regular expression behavior

Safe

Creates safe namespaces for evaluating Perl code

Scalar::Util

A selection of general-utility scalar subroutines (new in 5.8)

SDBM_File

Tied access to SDBM files

Search::Dict

Searches for key in dictionary file

SelectSaver

Saves and restores selected filehandle

SelfLoader

Loads functions only on demand

Shell

Runs shell commands transparently within Perl

sigtrap

Enables stack backtrace on unexpected signals

Socket

Loads the C socket.h defines and structure manipulators

sort

Perl pragma that controls sort behavior (new in 5.8)

Storable

Persistence for Perl data structures (new in 5.8)

strict

Restricts unsafe constructs

subs

Predeclares subroutine names

Switch

A switch statement for Perl (new in 5.8)

Symbol

Generates anonymous globs; qualifies variable names

Sys::Hostname

Tries every conceivable way to get hostname

Sys::Syslog

Perl interface to Unix syslog(3) calls

Term::Cap

Terminal capabilities interface

Term::Complete

Word completion module

Term::ReadLine

Interface to various ReadLine packages

Test

Framework for writing test scripts

Test::Builder

Backend for building text libraries (new in 5.8)

Test::Harness

Runs Perl standard test scripts with statistics

Test::More

Yet another framework for writing test scripts (new in 5.8)

Test::Simple

Basic utilities for writing tests (new in 5.8)

Text::Abbrev

Creates an abbreviation table from a list

Text::Balanced

Extracts delimited text sequences from strings (new in 5.8)

Text::ParseWords

Parses text into a list of tokens

Text::Soundex

The soundex algorithm described by Knuth

Text::Tabs

Expands and unexpands tabs

Text::Wrap

Wraps text into a paragraph

Thread

Multithreading support

Thread::Queue

Thread-safe queues

Thread::Semaphore

Thread-safe semaphores

Thread::Signal

Starts a thread that runs signal handlers reliably

Thread::Specific

Thread-specific keys

Tie::Array

Base class definitions for tied arrays

Tie::File

Accesses the lines of a disk file via a Perl array (new in 5.8)

Tie::Handle

Base class definitions for tied handles

Tie::Hash

Base class definitions for tied hashes

Tie::Memorize

Adds data to a hash when needed (new in 5.8)

Tie::RefHash

Uses references as hash keys

Tie::Scalar

Base class definitions for tied scalars

Tie::SubstrHash

Fixed table size, fixed key length hashing

Time::gmtime

By-name interface to Perl's built-in gmtime function

Time::HiRes

High-resolution alarm, sleep, gettimeofday, interval timers (new in 5.8)

Time::Local

Computes time from local and GMT time

Time::localtime

By-name interface to Perl's built-in localtime function

Time::tm

Internal object used by Time::gmtime and Time::localtime

UNIVERSAL

Base class for all classes (blessed references)

User::grent

By-name interface to Perl's built-in getgr* functions

User::pwent

By-name interface to Perl's built-in getpw* functions

utf8

Perl pragma to enable/disable UTF-8 in source code

vars

Predeclares global variable names

vmsish

Perl pragma that controls VMS-specific language features (new in 5.8)

XS::Typemap

Module that tests the XS typemaps distributed with Perl (new in 5.8)

In the remainder of this chapter, the modules are arranged in alphabetical order for easy reference. For more detail about a module, use the perldoc command to read the manpage for that module (see Chapter 4, "The Perl Language" for information on perldoc).

8.1. AnyDBM_File

Provides a single Database Manager (DBM) interface regardless of the DBM implementation you use. The module inherits from the various DBM packages; by default, it inherits from NDBM_File. If it doesn't find NDBM_File, the default search order is: DB_File, GDBM_File, SDBM_File (which comes with Perl), and finally, ODBM_File. You can override this default order by redefining @ISA:

@AnyDBM_File::ISA = qw(DB_File GDBM_File NDBM_File);

However, an explicit use takes priority over the @ISA ordering.

Perl's dbmopen function simply calls tie to bind a hash to AnyDBM_File. The effect is to bind the hash to one of the specific DBM classes that AnyDBM_File inherits from.

Chapter 8. Standard Modules

Contents:

8.1. AnyDBM_File


7.4. Object Syntax		8.2. Attribute::Handlers