Import into Python via String

Handles

import foobar
import foo.bar as baz
from foo import bar
from foo.bar import Baz
from foo.bar import BAZ

class HandlerRegistry(dict):
    def __missing__(self, name):
        if '.' not in name:
            handler = __import__(name)
        else:
            module_name, handler_name = name.rsplit('.', 1)

            module = __import__(module_name, {}, {}, [handler_name])
            handler = getattr(module, handler_name)

            self[name] = handler

        return handler

_HANDLER_REGISTRY = HandlerRegistry()

def import_handler(name):
    handler = _HANDLER_REGISTRY[name]
    return handler

To Use

>>> Sequence = import_handler('collections.Sequence')
>>> ndarray  = import_handler('numpy.ndarray')
>>> now      = import_handler('datetime.datetime.now')