UL4 – A templating language

ll.ul4c provides templating for XML/HTML as well as any other text-based format. A template defines placeholders for data output and basic logic (like loops and conditional blocks), that define how the final rendered output will look.

ll.ul4c compiles a template to an internal format, which makes it possible to implement renderers for these templates in multiple programming languages.

Note

Apart from this Python implementation there are implementations for Java (both a compiler and renderer) and Javascript (renderer only).

In the template source any text surrounded by <? and ?> is a “template tag”. The first word inside the tag is the tag type. It defines what the tag does. For example <?print foo?> is a print tag (it prints the value of the variable foo). A complete example template looks like this:

<?if data?>
   <ul>
      <?for item in data?>
         <li><?print xmlescape(item)?></li>
      <?end for?>
   </ul>
<?end if?>

A complete Python program that compiles a template and renders it might look like this:

from ll import ul4c

code = '''
   <?if data?>
      <ul>
         <?for item in data?>
            <li><?print item?></li>
         <?end for?>
      </ul>
   <?end if?>
'''

template = ul4c.Template(code)

print(template.renders(data=["Python", "Java", "Javascript", "PHP"]))

The variables that should be available to the template code can be passed to the method renders() as keyword arguments. renders() returns the final rendered output as a string. Alternatively the method render() can be used, which is writes the output to a text stream.

For more information see the following chapters:

Content