from django.template import Library, Node, TemplateSyntaxError
from uuid import uuid4

register = Library()

class UUIDNode( Node ):
    """
    Implements the logic of this tag.
    """
    def __init__( self, var_name ):
        self.var_name = var_name
        
    def render( self, context ):
        context[ self.var_name ] = str( uuid4() )
        return ''

def do_uuid( parser, token ):
    """
    The purpose of this template tag is to generate a random
    UUID and store it in a named context variable.
    
    Sample usage:
        {% uuid var_name %}
        var_name will contain the generated UUID
    """
    try:
        tag_name, var_name = token.split_contents()
    except ValueError:
        raise TemplateSyntaxError, "%r tag requires exactly one argument" % token.contents.split()[ 0 ]
    return UUIDNode( var_name )

do_uuid = register.tag( 'uuid', do_uuid )