Django set template tag

set_tags.py

from django import template


register = template.Library()


class SetNode(template.Node):
    def __init__(self, key, nodelist, return_result=False):
        self.key = key
        self.nodelist = nodelist
        self.return_result = return_result

    def render(self, context):
        value = self.nodelist.render(context)
        for d in context.dicts:
            d[self.key] = value
        if self.return_result:
            return value
        else:
            return ''


@register.tag
def set(parser, token, return_result=False):
    try:
        tag_name, key = token.split_contents()
    except ValueError:
        raise template.TemplateSyntaxError(
            '%r tag requires a single argument' %
            token.contents.split()[0])

    nodelist = parser.parse(('endset',))
    parser.delete_first_token()

    return SetNode(key, nodelist, return_result)


@register.tag
def setget(parser, token):
    return set(parser, token, return_result=True)