Random code tag

# -*- coding: UTF-8 -*-
from django import template
import string
import random
register = template.Library()
CODE_CHARS = string.ascii_uppercase+string.digits

@register.tag(name="randomCode")
def randomCode(parser, token):
	try:
		# split_contents() knows not to split quoted strings.
		tag_name, num = token.split_contents()
	except ValueError:
		raise template.TemplateSyntaxError, "%r tag requires an integer as a single argument" % token.contents.split()[0]
	if not (num[0] == num[-1] and num[0] in ('"', "'")):
		raise template.TemplateSyntaxError, "%r tag's argument should be in quotes and be a positive integer" % tag_name
	try:
		value = int(num[1:-1])
		if value <0:
			raise template.TemplateSyntaxError, "%r tag's argument must be a positive integer"
	except:
		raise template.TemplateSyntaxError, "%r tag's argument must be a positive integer" % tag_name
	return randomCodeNode(value)

class randomCodeNode(template.Node):
    def __init__(self, num):
		self.num = num
    def render(self, context):		
		try:
			codi = random.sample(CODE_CHARS,self.num)
		except ValueError, e:
			raise template.TemplateSyntaxError, "tag's argument must be a lower than %i" % len(CODE_CHARS)
		s = ''
		return s.join(codi)