"""@see http://www.b-list.org/weblog/2006/06/07/django-tips-write-better-template-tags
"""
from django.template import Library, Node
from django.db.models import get_model

register = Library()

class LatestContentNode(Node):
    def __init__(self, model, num, varname):
        self.num, self.varname = num, varname
        self.model = get_model(*model.split('.'))

    def render(self, context):
        context[self.varname] = self.model._default_manager.all()[:self.num]
        return''

def get_latest(parser, token):
    """
    {% get_latest weblog.Link 5 as recent_links %}
    {% get_latest weblog.Entry 10 as latest_entries %}
    {% get_latest comments.Comment 5 as recent_comments %}
    """
    bits = token.contents.split()
    if len(bits) != 5:
        raise TemplateSyntaxError, "get_latest tag takes exactly three arguments"
    if bits[3] != 'as':
        raise TemplateSyntaxError, "third argument to get_latest tag must be 'as'"
    return LatestContentNode(bits[1], bits[2], bits[4])
get_latest = register.tag(get_latest)