Hailstorm
Hailstorm is an open source Python templating library extracted from Facebook's Tornado, the non-blocking web server available at http://www.tornadoweb.org/
The key feature of Hailstorm is not restricting the kind of expressions that can be used in the statements within the template files. It's just Python so you don't need filters or template tags like in Jinja2 or Django templates. You just pass the objects you intend to use to the template and you're good to go.
Hailstorm is licensed under the Apache Licence, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0.html).
Usage
Basic usage looks like::
t = template.Template("<html>{{ myvalue }}</html>")
print t.generate(myvalue="XXX")
Loader is a class that loads templates from a root directory and caches the compiled templates::
loader = template.Loader("/home/gnrfan")
print loader.load("test.html").generate(myvalue="XXX")
We compile all templates to raw Python. Error-reporting is currently... uh, interesting. Syntax for the templates::
### base.html
<html>
<head>
<title>{% block title %}Default title{% end %}</title>
</head>
<body>
<ul>
{% for student in students %}
{% block student %}
<li>{{ escape(student.name) }}</li>
{% end %}
{% end %}
</ul>
</body>
</html>
### bold.html
{% extends "base.html" %}
{% block title %}A bolder title{% end %}
{% block student %}
<li><span style="bold">{{ escape(student.name) }}</span></li>
{% end %}
Unlike most other template systems, we do not put any restrictions on the expressions you can include in your statements. if and for blocks get translated exactly into Python, you can do complex expressions like:
{% for student in [p for p in people if p.student and p.age > 23] %}
<li>{{ escape(student.name) }}</li>
{% end %}
Translating directly to Python means you can apply functions to expressions easily, like the escape() function in the examples above. You can pass functions in to your template just like any other variable::
### Python code
def add(x, y):
return x + y
template.execute(add=add)
### The template
{{ add(1, 2) }}
We provide the functions escape(), url_escape(), json_encode(), and squeeze() to all templates by default.
Syntax Reference
Template expressions are surrounded by double curly braces: {{ ... }}.
The contents may be any python expression, which will be escaped according
to the current autoescape setting and inserted into the output. Other
template directives use {% %}. These tags may be escaped as {{!
and {%! if you need to include a literal {{ or {% in the output.
To comment out a section so that it is omitted from the output, surround it
with {# ... #}.
{% apply *function* %}...{% end %}
Applies a function to the output of all template code between apply
and end::
{% apply linkify %}{{name}} said: {{message}}{% end %}
Note that as an implementation detail apply blocks are implemented
as nested functions and thus may interact strangely with variables
set via ``{% set %}``, or the use of ``{% break %}`` or ``{% continue %}``
within loops.
{% autoescape *function* %}
Sets the autoescape mode for the current file. This does not affect
other files, even those referenced by {% include %}. Note that
autoescaping can also be configured globally, at the Application
or Loader.::
{% autoescape xhtml_escape %}
{% autoescape None %}
{% block *name* %}...{% end %}
Indicates a named, replaceable block for use with {% extends %}.
Blocks in the parent template will be replaced with the contents of
the same-named block in a child template.::
<!-- base.html -->
<title>{% block title %}Default title{% end %}</title>
<!-- mypage.html -->
{% extends "base.html" %}
{% block title %}My page title{% end %}
{% comment ... %}
A comment which will be removed from the template output. Note that
there is no {% end %} tag; the comment goes from the word comment
to the closing %} tag.
{% extends *filename* %}
Inherit from another template. Templates that use extends should
contain one or more block tags to replace content from the parent
template. Anything in the child template not contained in a block
tag will be ignored. For an example, see the {% block %} tag.
{% for *var* in *expr* %}...{% end %}
Same as the python for statement. {% break %} and
{% continue %} may be used inside the loop.
{% from *x* import *y* %}
Same as the python import statement.
{% if *condition* %}...{% elif *condition* %}...{% else %}...{% end %}
Conditional statement - outputs the first section whose condition is
true. (The elif and else sections are optional)
{% import *module* %}
Same as the python import statement.
{% include *filename* %}
Includes another template file. The included file can see all the local
variables as if it were copied directly to the point of the include
directive (the {% autoescape %} directive is an exception).
Alternately, {% module Template(filename, **kwargs) %} may be used
to include another template with an isolated namespace.
{% module *expr* %}
Renders a ~tornado.web.UIModule. The output of the UIModule is
not escaped::
{% module Template("foo.html", arg=42) %}
{% raw *expr* %}
Outputs the result of the given expression without autoescaping.
{% set *x* = *y* %}
Sets a local variable.
{% try %}...{% except %}...{% finally %}...{% else %}...{% end %}
Same as the python try statement.
{% while *condition* %}... {% end %}
Same as the python while statement. {% break %} and
{% continue %} may be used inside the loop.
On the "Hailstorm" name
""" I guess the ideal name was 'Tempest' but there already was a package named like that in PyPi so I went with this name since one of my new favorite hard rock bands is Halestorm! """ -Antonio Ognio
(c) 2013, Bit Zeppelin S.A.C - Lima, Peru.
