Template tag to check to check is a particular URL is active

templatetags.py

class NavSelectedNode(template.Node):
    def __init__(self, obj, var):
        self.obj = obj
        self.var = var
		
	def render(self, context):
	    value = template.Variable(self.obj).resolve(context)
	    context[self.var] = False
	    path = context['request'].path
            # Here we can do some more complicated parsing of the current URL against our passed URL
	    if (path.startswith(value)) or (value == path):
	        context[self.var] = True
		return ""
			
@register.tag
def is_active(parser, token):
    """Check if the provided string pattern is the current url"""
    args = token.split_contents()
    template_tag = args[0]
    if len(args) != 4:
        raise template.TemplateSyntaxError, "%r tag should be in the form {%% is_active [obj] as [variable] %%}" % template_tag
    return NavSelectedNode(args[1], args[3])

# {% url someview as an_url %}
# {% is_active an_url as is_home_page %}
# {% if is_home_page %}...{% endif %}