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Python templating engine - the one ton solution

Project description


Tonnikala is the latest reincarnation among the Python templating languages that feed on Kid-inspired XML syntax. It rejects the Kid and Genshi notions of tagstreams and trees, and follows in footsteps of Chameleon and Kajiki in making the template to compile into Python bytecode directly. The syntax is very close to that of Kajiki, but the internals are very different: Tonnikala writes code as Abstract Syntax Trees and optimizes the resulting trees extensively. In addition, there is an optional speed-up module (currently Python 3 only), that provides a specialized class used for output buffering.


from tonnikala.loader import Loader

template_source = u"""
    <tr py:for="row in table">
        <py:for each="key, value in row.items()"

template = Loader().load_string(template_source)

ctx = {
    'table': [dict(a=1,b=2,c=3,d=4,e=5,f=6,g=7,h=8,i=9,j=10)
        for x in range(1000)]


Template inheritance

<title><py:block name="title_block">I am ${title}</py:block></title>
<py:def function="foo()">I can be overridden too!</py:def>

<py:extends href="">
<py:block name="title_block">But I am ${title} instead</py:block>
<py:def function="foo()">I have overridden the function in parent template</py:def>

Template imports

<py:def function="foo()">I am an importable function</py:def>

<py:import href="" alias="imp" />


To load templates from files, use the tonnikala.FileLoader class:

loader = FileLoader(paths=['/path/to/templates'])
template = loader.load('')

A FileLoader currently implicitly caches all loaded templates in memory.


To render the template:

result = template.render(ctx)

You can specify a block, or no-argument def to render explicitly:

result = template.render(ctx, funcname='title_block')

Pyramid integration

Include ‘tonnikala.pyramid’ into your config to enable Tonnikala. When included, tonnikala adds the following configuration directives:


Registers tonnikala renderer for these template extensions. By default Tonnikala is not registered as a renderer for any extension. For example: config.add_tonnikala_extensions(‘.html’, ‘.tk’) would enable Tonnikala renderer for templates with either of these extensions.


Adds the given paths to the end of Tonnikala search paths that are searched for templates. These can be absolute paths, or package.module:directory/subdirectory-style asset specs. By default no paths are searched explicitly (but you can always use an asset spec for template.


If True, makes tonnikala not cache templates. Default is False.

These 3 can also be controlled by tonnikala.extensions, tonnikala.search_paths and tonnikala.reload in .ini settings.


Alpha, working features are

  • Structural elements py:if, py:unless, py:def, py:for, py:replace, py:content

  • Basic template inheritance: py:extends and py:block; the child template also inherits top level function declarations from the parent template, and the child can override global functions that the parent defines and uses.

  • Expression interpolation using $simple_identifier and ${complex + python + "expression"}

  • Boolean attributes: <tag attr="${False}">, <tag attr="$True">

  • Implicit escaping

  • Disabling implicit escaping (literal())

  • C speedups for both Python 2 and Python 3

  • Importing def blocks from another template: py:import

  • Basic I18N using gettext.

  • Pyramid integration

Upcoming features:

  • Structural elements: py:vars, py:switch, py:case; py:else for for, if and switch.

  • Overriding attributes, setting attrs from dictionary: py:attrs

  • Custom tags mapping to py:def

  • I18N with optional in-parse-tree localization (partially done)

  • Javascript as the target language

  • Pluggable frontend syntax engines (partially done)

  • METAL-like macros

  • Pluggable expression languages akin to Chameleon

  • Even better template inheritance

  • Better documentation


Antti Haapala

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