{% eval %} templatetag-evaluate expressions

from django import template

register = template.Library()

@register.tag(name='eval')
def do_eval(parser, token):
    "Usage: {% eval %}1 + 1{% endeval %}"

    nodelist = parser.parse(('endeval',))

    class EvalNode(template.Node):
        def render(self, context):
            return eval(nodelist.render(context))
 
    parser.delete_first_token()
    return EvalNode()