z3c.pt 0.8.5

An implementation of the TAL template language.

Overview

The z3c.pt package provides an alternative implementation of the TAL template language including i18n. It also provides a simple text template class that allows expression interpolation.

Casual benchmarks pegs it 11x more performant than zope.pagetemplate.

In a nutshell:

• Templates are parsed and compiled into Python bytecode

• While rendering only Python code is executed and no parsing happens

• Pluggable expression implementation

• Support for expression interpolation using the ${<expression>}-format

• Non-XML friendly

Note: The METAL macro language is not supported.

Usage

See README.txt inside package for general usage; to register the default expression types, load the package component configuration file (configure.zcml).

Template and expression language

The template and expression language is based loosely on the TAL 1.4 specification*. Some notable changes:

1. Tuples are allowed in the tal:define statement:

   tal:define=”(a, b, c) [1, 2, 3]”

2. Generators are allowed in tal:repeat statements. Note that the repeat variable is not available in this case.

   tal:repeat=”i <some generator>”

3. Attribute-access to dictionary entries is allowed in Python-expressions, e.g.

   dictionary.key

   can be used instead of dictionary['key'].

4. Expression interpolation is allowed in attributes and HTML content.

   <a href=”mailto:${context.email}”>${context.email}</a>

5. Default expression type can be set using tal:default-expression. This is an alternative to providing the expression type before each expression.

Development

If you want to use the code directly from trunk (recommended only for development and testing usage), provide z3c.pt==dev as your dependency.

http://svn.zope.org/z3c.pt/trunk#egg=z3c.pt-dev

Changelog

Version 0.8.x

• Fixed interpolation edge case bugs. [malthe]

• Added new Z3C_PT_FILECACHE environment variable pointing to a directory. If set, this will be used to cache the compiled files.

• Added a second variation of the repeat clause, using a simple for loop. It doesn’t support the repeatdict, though and is therefor not used yet. Also began work to add introspection facilities to clauses about the variables being used in them. The simpler loop causes the benchmarks to go up to a 10.5 (old 9.5) for path expressions and 14.5 (12.5) for python expressions. So the next step is to introduce an optimization phase, that can decide which variant of the loops to use.

• Made the debug mode independent from the Python debug mode. You can now specify an environment variable called Z3C_PT_DEBUG to enable it.

• Added some code in a filecache module that can later be used to write out and reload the compiled Python code to and from the file system. We should be able to avoid reparsing on Python process restart.

• Simplified the generated _escape code. cgi.escape’s second argument is a simple boolean and not a list of characters to quote.

• Use a simple list based BufferIO class instead of a cStringIO for the out stream. Avoiding the need to encode Unicode data is a bigger win. We do not support arbitrarily mixing of Unicode and non-ascii inside the engine.

• Merged two adjacent writes into one inside the Tag clause.

• Applied a bunch of micro-optimizations. ‘’.join({}) is slightly faster than ‘’.join({}.keys()) and does the same. Avoid a try/except for error handling in non-debug mode. Test against ‘is None’ instead of a boolean check for the result of the template registry lookup. Made PROD_MODE available defined as ‘not DEBUG_MODE’ in config.py, so we avoid the ‘not’ in every cook-check.

• Added more benchmark tests for the file variants.

• Optimized ‘is None’ handling in Tag clause similar to the Write clause.

• Made the _out.write method directly available as _write in all scopes, so we avoid the method lookup call each time.

• Optimized ‘is None’ handling in Write clause.

• Slightly refactored benchmark tests and added tests for the file variants.

• In debug mode the actual source code for file templates is written out to a <filename>.source file, to make it easier to inspect it.

• Make debug mode setting explicit in a config.py. Currently it is bound to Python’s __debug__, which is False when run with -O and otherwise True.

• Use a simplified UnicodeWrite clause for the result of _translate calls, as the result value is guaranteed to be Unicode.

• Added benchmark tests for i18n handling.

• Added more tests for i18n attributes handling.

• Don’t generate empty mappings for expressions with a trailing semicolon.

• Fixed undefined name ‘static’ error in i18n attributes handling and added quoting to i18n attributes.

• Added condition to the valid attributes on tags in the tal namespace.

• Made sure the traceback from the first template exception is carried over to __traceback_info__

• Added template source annotations on exceptions raised while rendering a template.

Version 0.8 - March 19, 2008

• Added support for ‘nocall’ and ‘not’ (for path-expressions).

• Added support for path- and string-expressions.

• Abstracted expression translation engine. Expression implementations are now pluggable. Expression name pragmas are supported throughout.

• Formalized expression types

• Added support for ‘structure’-keyword for replace and content.

• Result of ‘replace’ and ‘content’ is now escaped by default.

• Benchmark is now built as a custom testrunner

Version 0.7 - March 10, 2008

• Added support for comments; expressions are allowed inside comments, i.e.

  <!– ${‘Hello World!’} –>

  Comments are always included.

Version 0.6 - February 24, 2008

• Added support for text templates; these allow expression interpolation in non-XML documents like CSS stylesheets and javascript files.

Version 0.5 - February 23, 2008

• Expression interpolation implemented.

Version 0.4 - February 22, 2008

• Engine now uses cStringIO yielding a 2.5x performance improvement. Unicode is now handled correctly.

Version 0.3 - December 23, 2007

• Code optimization; bug fixing spree

• Added ViewPageTemplateFile class

• Added support for i18n

• Engine rewrite; improved code generation abstractions

Version 0.2 - December 5, 2007

• Major optimizations to the generated code

Version 0.1 - December 3, 2007

• First public release