Template Tag Render Decorator

"""
A decorator that abstracts away the boilerplate code around creating a template 
node class which is the same each and every time you simply want a templatetag 
with access to the template context and the calling token.

Usage:

@register_render_tag
def my_tag(context, token):
    # parse the token and modify the context
    return "" 

Credits:
--------

Stephen McDonald <[email protected]>

License:
--------

Creative Commons Attribution-Share Alike 3.0 License
http://creativecommons.org/licenses/by-sa/3.0/

When attributing this work, you must maintain the Credits
paragraph above.
"""

from django import template


register = template.Library()


def register_render_tag(renderer):
    """
    Decorator that creates a template tag using the given renderer as the 
    render function for the template tag node - the render function takes two 
    arguments - the template context and the tag token
    """
    def tag(parser, token):
        class TagNode(template.Node):
            def render(self, context):
                return renderer(context, token)
        return TagNode()
    for copy_attr in ("__dict__", "__doc__", "__name__"):
        setattr(tag, copy_attr, getattr(renderer, copy_attr))
    return register.tag(tag)