PHP Programming Language - Cultural View

PEAR 166
PEAR
The PHP Extension and Application Repository, or PEAR, is a repository of PHP software code. Stig S. Bakken
founded the PEAR project in 1999 to promote the re-use of code that performs common functions. The project seeks
to provide a structured library of code, maintain a system for distributing code and for managing code packages, and
promote a standard coding style. Though community-driven, the PEAR project has a PEAR Group which serves as
the governing body and takes care of administrative tasks. Each PEAR code package comprises an independent
project under the PEAR umbrella. It has its own development team, versioning-control and documentation.
PEAR packages
A PEAR package is distributed as a gzipped tar file. Each archive consists of source code written in PHP, usually in
an object-oriented style. Many PEAR packages can readily be used by developers as ordinary third party code via
simple include statements in PHP. More elegantly, the PEAR package manager which comes with PHP by default
may be used to install PEAR packages so that the extra functionality provided by the package appears as an
integrated part of the PHP installation. Unlike the Comprehensive Perl Archive Network (CPAN) archives, which
PEAR took as its model, PEAR packages do not have implicit dependencies so that a package's placement in the
PEAR package tree does not relate to code dependencies. Rather, PEAR packages must explicitly declare all
dependencies on other PEAR packages.
The PEAR base classes contain code for simulating object-oriented destructors and consistent error-handling.
Packages exist for many basic PHP functions including authentication, caching, database access, encryption,
configuration, HTML, web services and XML.
PEAR package manager
The PEAR package manager provides an easy way to install, uninstall, or upgrade with new PEAR packages or
PECL extensions. Before installing a package it can also be instructed to take care of package dependencies so all
the extra needed packages are installed too.
The PEAR package manager is run from the command line using the pear command. Usually it is therefore only the
server administrator who can alter the installed base of PEAR and PECL extensions. On PHP installations running
on Linux, the PEAR package manager is ready for usage by default, but on Windows the PEAR package manager is
only available after running a batch file called go-pear.bat.
PECL
PECL (PHP Extension Community Library, pronounced 'pickle') is conceptually very similar to PEAR, and indeed
PECL modules are installed with the PEAR Package Manager. PECL contains C extensions for compiling into PHP.
As C programs , PECL extensions run more efficiently than PEAR packages. PECL includes modules for
XML-parsing, access to additional databases, mail-parsing, embedding Perl or Python in PHP scripts and for
compiling PHP scripts. PECL spun off from the PEAR Project in October 2003. Originally it was called the PEAR
Extension Code Library, but it now operates independently of PEAR.
PECL extensions are documented alongside standard extensions within the PHP Manual, so there is no special
manual for PECL extensions. Also, several extensions began their development cycle in PECL and ended up in core
(the distributed PHP source) and in many of these cases the PECL versions become unmaintained.