from django import template

register = template.Library()

class SetContextNode(template.Node):
  """
  This class defines renderer which just updates current template context with the rendered output of the block inside tags.
  """
  def __init__(self, nodelist, variable):
    self.nodelist = nodelist
    self.variable = variable
  
  def render(self, context):
    context[self.variable] = self.nodelist.render(context)
    return ''

@register.tag
def setcontext(parser, token):
  """
  Sets (updates) current template context with the rendered output of the block inside tags.
  """
  nodelist = parser.parse(('endsetcontext',))
  args = list(token.split_contents())
  
  if len(args) != 3 or args[1] != "as":
    raise TemplateSyntaxError("%r expected format is 'as name'" % args[0])
  variable = args[2]
  
  parser.delete_first_token()
  
  return SetContextNode(nodelist, variable)