Kid Namespace Change

The Kid namespace has changed from http://naeblis.cx/ns/kid# to http://purl.org/kid/ns#. The naeblis.cx domain is privately owned and could expire some time in the future. purl.org is a system for establishing and maintaining "persistent" URIs.

A temporary hack has been put in place to substitute references to the old namespace URI with the new namespace URI. A warning is output when this occurs. This will be removed in a couple of months so it is recommended that templates be upgraded as soon as possible.

py:omit is now py:strip

Due to initial confusion many experienced with the name py:omit, it has been renamed py:strip. The term "omit" was often read as "omit the element and all descendants". The new term "strip" seems to better indicate the semantic: "strip the start and end tag but process descendants."

Python Expression Substitution Syntax

The syntax of brace expansions has been modified match more closely with existing Python substitution syntax. In 0.5 python expressions enclosed in curly braces ({}) were evaluated and their results substituted. In 0.6, the rules have changed as follows:

1. $$ is an escape; it is replaced with a single $.
2. $name substitutes a variable value.
3. ${expr} substitutes the result of evaluating any python expression.

See Python Expression Substitution in the Language Reference.

cElementTree Support

Kid now uses cElementTree if it is available. Preliminary tests show moderate performance increases. In most cases, we're seeing template parse and execution time increase by about 15%. The poor increase (relative to other cET/ET numbers) is due to the fact that we're not using cElementTree's native parser as it doesn't support comments or processing instructions. The plan is to lobby the effbot organization to add these features (hint, hint: send patches) so that we can get the huge increases people are seeing elsewhere.

Kid automatically determines whether cElementTree is available and uses it if so. If cElementTree is not available, Kid falls back on Python ElementTree. If you want to turn off use of cElementTree, you can set the environment variable KID_NOCET to 1.

Death of Comment Wart

In versions of Kid prior to 0.6, the first line of an embedded Python code block had to be a Python comment (#). This was due to Python's whitespace semantics. Christoph determined a process for establishing the correct indent levels without requiring a comment as the first line.

Starting in Kid 0.6, a comment is no longer required to be the first line in a <?python?> processing instruction. It is also possible to have single line code blocks:

<?python x = 10 ?>

Improved Template API

The Python interfaces have been reworked significantly and now are very similar to Cheetah's. There are two preferred methods for accessing a template.

import kid ; kid.enable_import()
import mytemplate
template = mytemplate.Template(foo='bar', bling=1)
print template.serialize()

template = mytemplate.Template()
template.foo = 'bar'
template.bling = 1
print str(template)

from kid import Template
# create a template from file
template = Template(file='mytemplate.kid', foo='bar', bling=1)

# create a template from string
template = Template(source="<p>${foo}</p>", foo='bar')

# create a template from a python module name
template = Template(name='templates.mytemplate', foo='bar')

Match Templates / Filters

Match Templates are a cross between XSLT's match templates and JSP tag libraries. They allow a set of filters to be put in place that matches infoset items generated by a template so that output can be modified.

While match templates provide a general purpose mechanism for transforming XML content, it is especially useful in a couple of situations which have driven the design:

1. Creating tag libraries that inject new tags into an XML vocabulary.
2. Applying headers/footers without inserting place-holders into the source document/template.

See Match Templates in the Language Reference for more information.

Template Inheritance

Templates now support multiple inheritance of template functions (py:def) and match templates (py:match). A template indicates that it extends one or more other templates by setting the py:extends attribute on the root element:

<?xml version='1.0' encoding='utf-8'?>
<html py:extends="'common.kid', 'forms.kid'" ...

py:extends may contain template modules, Template classes, or strings specifying template paths relative to current template file.

See Template Reuse in the Language Reference for more information.

Dynamic Attribute Generation (py:attrs)

A new py:attrs attribute has been added that allows attributes to be specified using a dictionary.

See Dynamic Attributes in the Language Reference for more information.