Import any python callback

import_callback.py

"""


Currently with django we can only import an attribute from a module, not a sub-attribute. For example

import_string('foo.models.YourModel')  # works
import_string('foo.models.YourModel.objects.update_stats')  # doesn't

This snippet fixes that, originally for django-call which has tests.

"""
from django.utils.module_loading import import_string


def import_callback(callback):
    parts = callback.split('.')
    i = callback.count('.')
    while i:
        try:
            mod = import_string('.'.join(parts[:i + 1]))
        except ImportError:
            if not i:
                raise
            i -= 1
        else:
            ret = mod 
            while 0 < i < callback.count('.'):
                ret = getattr(ret, parts[len(parts) - i]) 
                i -= 1
            return ret