PHP Extension and Application Repository
Encyclopedia
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 package
s, 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.
ped 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 class
es contain code for simulating object-oriented
destructor
s and consistent error-handling. Packages exist for many basic PHP functions including authentication
, caching
, database access, encryption
, configuration, HTML
, web services and XML
.
The PEAR package manager is run from the command line using the
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.
PHP
PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...
software code. Stig S. Bakken founded the PEAR project in 1999 to promote the re-use
Code reuse
Code reuse, also called software reuse, is the use of existing software, or software knowledge, to build new software.-Overview:Ad hoc code reuse has been practiced from the earliest days of programming. Programmers have always reused sections of code, templates, functions, and procedures...
of code that performs common functions. The project seeks to provide a structured library
Library (computer science)
In computer science, a library is a collection of resources used to develop software. These may include pre-written code and subroutines, classes, values or type specifications....
of code, maintain a system for distributing code and for managing code package
Package
Package can refer to:* Packaging and labeling* Package testing* Mail item larger than a letter* Chip package or chip carrier, in electronics, the material added around a component or integrated circuit to allow it to be handled without damage and incorporated into a circuit* Automotive package, in...
s, 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 gzipGzip
Gzip is any of several software applications used for file compression and decompression. The term usually refers to the GNU Project's implementation, "gzip" standing for GNU zip. It is based on the DEFLATE algorithm, which is a combination of Lempel-Ziv and Huffman coding...
ped tar file. Each archive consists of source code written in PHP
PHP
PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...
, 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
CPAN, the Comprehensive Perl Archive Network, is an archive of nearly 100,000 modules of software written in Perl, as well as documentation for it. It has a presence on the World Wide Web at and is mirrored worldwide at more than 200 locations...
(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 class
Class (computer science)
In object-oriented programming, a class is a construct that is used as a blueprint to create instances of itself – referred to as class instances, class objects, instance objects or simply objects. A class defines constituent members which enable these class instances to have state and behavior...
es contain code for simulating object-oriented
Object-oriented programming
Object-oriented programming is a programming paradigm using "objects" – data structures consisting of data fields and methods together with their interactions – to design applications and computer programs. Programming techniques may include features such as data abstraction,...
destructor
Destructor (computer science)
In object-oriented programming, a destructor is a method which is automatically invoked when the object is destroyed...
s and consistent error-handling. Packages exist for many basic PHP functions including authentication
Authentication
Authentication is the act of confirming the truth of an attribute of a datum or entity...
, caching
Cache
In computer engineering, a cache is a component that transparently stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere...
, database access, encryption
Encryption
In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...
, configuration, HTML
HTML
HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
, web services and XML
XML
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
.
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 CC (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
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
Perl
Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
or Python
Python (programming language)
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
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.