HTML_Template_Sigma implements Integrated Templates API designed by Ulf Wendel.

Features:
  * Nested blocks. Nesting is controlled by the engine.
  * Ability to include files from within template: <!-- INCLUDE -->
  * Automatic removal of empty blocks and unknown variables
    (methods to manually tweak/override this are also available)
  * Methods for runtime addition and replacement of blocks in templates
  * Ability to insert simple function calls into templates:
    func_uppercase('Hello world!') and to define callback functions for these
  * 'Compiled' templates: the engine has to parse a template file using regular
    expressions to find all the blocks and variable placeholders.
    This is a very "expensive" operation and is an overkill to do on every page
    request: templates seldom change on production websites.
    Thus this feature: an internal representation of the template structure is
    saved into a file and this file gets loaded instead of the source one on
    subsequent requests (unless the source changes)
  * PHPUnit-based tests to define correct behaviour
  * Usage examples for most of the features are available, look in the docs/
    directory

WWW: http://pear.php.net/package-info.php?package=HTML_Template_Sigma