Chameleon is an HTML/XML¹ template language compiler.

It includes a feature-complete engine for the Zope Page Templates (ZPT) language.

The software is released on PyPi. To download and install the latest release:

$ easy-install -U Chameleon

This library has been successfully tested on the following platforms:

• Python 2.5, 2.6, 2.7
• Python 3.1, 3.2
• PyPy

The 2.x series is a complete rewrite of the library and supports both Python 2.5+ and Python 3.1+ with a single source code.

For most users it should be an easy upgrade, however note that at present, there is no engine for the Genshi language.

This series features a new parser, implemented in pure Python. It parses both HTML and XML inputs (the previous parser relied on the expat system library and was more strict about its input).

The 2.x engine matches the output of the reference implementation more closely (usually exactly). There are less differences altogether; for instance, the method of escaping TALES expression (usually a semicolon) has been changed to match that of the reference implementation.

This series also introduces a number of new language features:

1) Support for the tal:on-error from the reference specification has been added.

2) Inspired by the Genshi language, a pair of new attributes has been added: tal:switch and tal:case, allowing flexible conditions.

The expression engine has been redesigned to make it easier to understand and extend.

The engine is built on the ast module (available since Python 2.6; backports included for Python 2.5).

The compiler output has been optimized for complex templates. For most applications, the engine should perform similarly to the 1.x series.

Very simple templates with tight loops (such as that of the "big table" benchmark) will see a decrease in performance. The compiler is optimized for dynamic variable scope and this lowers performance for templates that require only a static scope.

This software is made available as-is under a BSD-like license ² (see included copyright notice).