Pylons (web framework)

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Pylons
Image:pylons-tower-dark1.png
Developed by Ben Bangert, James Gardner
Latest release 0.9.7 / February 23, 2009
Written in Python
Operating system Cross-platform
Type Web application framework
License BSD License
Website www.pylonshq.com

Pylons is an open source web application framework written in Python. It makes extensive use of the Web Server Gateway Interface standard to promote reusability and to separate functionality into distinct modules.

Pylons is the newest of the current crop of web application frameworks, which also includes Django and TurboGears. It is strongly influenced by Ruby on Rails: two of its main components, Routes and WebHelpers, are Python reimplementations of Rails features.

Contents

[edit] Structure

Pylons is well-known for having a near-complete stack of third-party tools, eschewing definitively the "not–invented–here" phenomenon[citation needed].

[edit] Installation, dependencies, and setup

The official installation method of Pylons is through EasyInstall via the Python CheeseShop, and most of the additional tools are typically installed the same way. EasyInstall also handles package dependencies when relevant. Some distributions could also package Pylons and Paste, but it is likely that any distribution's packages would lag the official distribution. Pylons may also be installed by hand by renaming its .egg file to .zip and extracting the contents. However, it is often necessary to construct additional Pylons.

Paste is used for project setup, testing, and deployment. Using the common INI configuration format, Paste allows for multiple "profiles", so that developers can run development and deployment setups from the same codebase without revealing sensitive parts of Pylons, such as the interactive debugger, to production users.

[edit] URL dispatch

Currently the only widely used URL dispatcher for Pylons is Routes, a Python reimplementation of Ruby on Rails' URL dispatching, although any WSGI-compatible URL dispatcher can be used. While Routes is a separate library, it was developed for use in Pylons and its development remains closely in sync with Pylons.

[edit] HTML generation

Another piece of Rails adapted for Pylons is WebHelpers, which provides URL mapping based on the Routes configuration. WebHelpers also provides some utility functions for generating JavaScript code making use of the script.aculo.us and Prototype libraries.

FormEncode and FormBuild are used for HTML form validation and generation; there has been some use of Mako for form generation using Mako's inheritance model.

[edit] Templating

Myghty was the default Pylons templating language, but as of version 0.9.6 it has been replaced by Mako.[1] Both templating languages are text-based (as opposed to XML-based), and support includes, inheritance and embedding arbitrary Python code.

Because of Pylons' loosely coupled layers, other templating languages can be used as well. Genshi, an XML-based templating language, can be used in lieu of either Mako or Myghty. [2]

[edit] Database abstraction and object-relational mapping

Pylons has no default database library. Both SQLObject and SQLAlchemy are known to be used.

[edit] See also

[edit] Mailing List

Information taken from Google Groups as of Jan 10th, 2008:

  • 1211 Members
  • 284 Average messages per month (3 preceding months)

[edit] References

  1. ^ Haas, Christoph Beginning Pylons. Retrieved July 5, 2007
  2. ^ Genshi Wiki Pylons with Genshi Retrieved July 5 2007

[edit] External links

Packages used by the default Pylons installation, or popular additions:

  • Mako - Default templating engine for Pylons
  • Myghty - URL Dispatch, Controllers, Caching, Templating and more
  • Python Paste - Project setup, testing, and deployment
  • WebOb - Request and Response objects
  • EasyInstall - Installation and package dependencies
  • Routes - Routing implementation based on Rails routes
  • FormEncode - Validation and form generation
  • WebHelpers - HTML Helper functions
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