#coding:utf-8
'''
Created on 2012-12-19
@author: yihaomen.com
计算多个数的乘积
'''
from django import template
from django.template.base import resolve_variable, Node, TemplateSyntaxError
register = template.Library()
class MulTag(Node):
  def __init__(self,numList):
    self.numList = numList
  def render(self, context):
    realList = []
    try:
      for numobj in self.numList:
        realList.append(numobj.resolve(context))
    except:
      raise TemplateSyntaxError("multag error")
    try:
      value = realList[0]
      for num in realList[1:]:
        value = value* num
      return round(value,2)
    except:
      return ''
@register.tag(name="mymul")
def getMulNums(parser, token):
  bits = token.contents.split()
  realList = [parser.compile_filter(x) for x in bits[1:]]
  return MulTag(realList)

{% load myMulTag %}
{%mymul order.num item.price item.discount%}