Import module and/or symbol dynamically from name (string)

importer.py

import importlib

class Importer(object):
    @staticmethod
    def import_module(module_name):
        return importlib.import_module(module_name)    

    @staticmethod
    def get_symbol(symbol_name):
        module_name = Importer._extract_module_name(symbol_name)
        final_symbol_name = Importer._extract_final_symbol_name(symbol_name)
        module = importlib.import_module(module_name)
        try:
            return getattr(module, final_symbol_name)
        except AttributeError:
            raise ImportError()

    @staticmethod
    def _extract_module_name(symbol_name):
        return '.'.join(symbol_name.split('.')[:-1])

    @staticmethod
    def _extract_final_symbol_name(symbol_name):
        return symbol_name.split('.')[-1:][0]
    
    
import_module = Importer.import_module
get_symbol = Importer.get_symbol

test_importer.py

import unittest

from hamcrest import *

import importer
        
class ImporterTest(unittest.TestCase):
    def test_import_os_by_name(self):
        imported_os = importer.import_module('os')
        import os
        assert_that(imported_os, equal_to(os))
        
    def test_import_os_path(self):
        imported_os_path= importer.import_module('os.path')
        import os.path
        assert_that(imported_os_path, equal_to(os.path))
    
    def test_try_to_import_not_existing_module_should_raise_import_error(self):
        self.assertRaises(ImportError, importer.import_module, 'whatever')
    
    def test_get_isdir_function_by_name(self):
        import os.path
        assert_that(importer.get_symbol('os.path.isdir'), equal_to(os.path.isdir))
    
    def test_non_existing_symbol_should_raise_import_error(self):
        self.assertRaises(ImportError, importer.get_symbol, 'os.path.whatever')
    
if __name__ == "__main__":
    unittest.main()