python类import_string()的实例源码

def get_connection(backend=None, fail_silently=False, **kwds):
    """Load an email backend and return an instance of it.

    If backend is None (default) settings.EMAIL_BACKEND is used.

    Both fail_silently and other keyword arguments are used in the
    constructor of the backend.
    """
    klass = import_string(backend or settings.EMAIL_BACKEND)
    return klass(fail_silently=fail_silently, **kwds)

def get_password_validators(validator_config):
    validators = []
    for validator in validator_config:
        try:
            klass = import_string(validator['NAME'])
        except ImportError:
            msg = "The module in NAME could not be imported: %s. Check your AUTH_PASSWORD_VALIDATORS setting."
            raise ImproperlyConfigured(msg % validator['NAME'])
        validators.append(klass(**validator.get('OPTIONS', {})))

    return validators

def get_hashers():
    hashers = []
    for hasher_path in settings.PASSWORD_HASHERS:
        hasher_cls = import_string(hasher_path)
        hasher = hasher_cls()
        if not getattr(hasher, 'algorithm'):
            raise ImproperlyConfigured("hasher doesn't specify an "
                                       "algorithm name: %s" % hasher_path)
        hashers.append(hasher)
    return hashers

def load_backend(path):
    return import_string(path)()

def get_finder(import_path):
    """
    Imports the staticfiles finder class described by import_path, where
    import_path is the full Python path to the class.
    """
    Finder = import_string(import_path)
    if not issubclass(Finder, BaseFinder):
        raise ImproperlyConfigured('Finder "%s" is not a subclass of "%s"' %
                                   (Finder, BaseFinder))
    return Finder()

def default_storage(request):
    """
    Callable with the same interface as the storage classes.

    This isn't just default_storage = import_string(settings.MESSAGE_STORAGE)
    to avoid accessing the settings at the module level.
    """
    return import_string(settings.MESSAGE_STORAGE)(request)

def setUpClass(cls):
        if not os.environ.get('DJANGO_SELENIUM_TESTS', False):
            raise SkipTest('Selenium tests not requested')
        try:
            cls.selenium = import_string(cls.webdriver_class)()
        except Exception as e:
            raise SkipTest('Selenium webdriver "%s" not installed or not '
                           'operational: %s' % (cls.webdriver_class, str(e)))
        # This has to be last to ensure that resources are cleaned up properly!
        super(AdminSeleniumWebDriverTestCase, cls).setUpClass()

def construct_managers(self):
        "Deep-clone the managers using deconstruction"
        # Sort all managers by their creation counter
        sorted_managers = sorted(self.managers, key=lambda v: v[1].creation_counter)
        for mgr_name, manager in sorted_managers:
            mgr_name = force_text(mgr_name)
            as_manager, manager_path, qs_path, args, kwargs = manager.deconstruct()
            if as_manager:
                qs_class = import_string(qs_path)
                yield mgr_name, qs_class.as_manager()
            else:
                manager_class = import_string(manager_path)
                yield mgr_name, manager_class(*args, **kwargs)

def routers(self):
        if self._routers is None:
            self._routers = settings.DATABASE_ROUTERS
        routers = []
        for r in self._routers:
            if isinstance(r, six.string_types):
                router = import_string(r)()
            else:
                router = r
            routers.append(router)
        return routers

def template_context_processors(self):
        context_processors = _builtin_context_processors
        context_processors += tuple(self.context_processors)
        return tuple(import_string(path) for path in context_processors)

def get_default_exception_reporter_filter():
    # Instantiate the default filter for the first time and cache it.
    return import_string(settings.DEFAULT_EXCEPTION_REPORTER_FILTER)()

def load_handler(path, *args, **kwargs):
    """
    Given a path to a handler, return an instance of that handler.

    E.g.::
        >>> from django.http import HttpRequest
        >>> request = HttpRequest()
        >>> load_handler('django.core.files.uploadhandler.TemporaryFileUploadHandler', request)
        <TemporaryFileUploadHandler object at 0x...>
    """
    return import_string(path)(*args, **kwargs)

def get_storage_class(import_path=None):
    return import_string(import_path or settings.DEFAULT_FILE_STORAGE)

def get_cookie_signer(salt='django.core.signing.get_cookie_signer'):
    Signer = import_string(settings.SIGNING_BACKEND)
    key = force_bytes(settings.SECRET_KEY)
    return Signer(b'django.http.cookies' + key, salt=salt)

def get_internal_wsgi_application():
    """
    Loads and returns the WSGI application as configured by the user in
    ``settings.WSGI_APPLICATION``. With the default ``startproject`` layout,
    this will be the ``application`` object in ``projectname/wsgi.py``.

    This function, and the ``WSGI_APPLICATION`` setting itself, are only useful
    for Django's internal server (runserver); external WSGI servers should just
    be configured to point to the correct application object directly.

    If settings.WSGI_APPLICATION is not set (is ``None``), we just return
    whatever ``django.core.wsgi.get_wsgi_application`` returns.
    """
    from django.conf import settings
    app_path = getattr(settings, 'WSGI_APPLICATION')
    if app_path is None:
        return get_wsgi_application()

    try:
        return import_string(app_path)
    except ImportError as e:
        msg = (
            "WSGI application '%(app_path)s' could not be loaded; "
            "Error importing module: '%(exception)s'" % ({
                'app_path': app_path,
                'exception': e,
            })
        )
        six.reraise(ImproperlyConfigured, ImproperlyConfigured(msg),
                    sys.exc_info()[2])

def get_key_func(key_func):
    """
    Function to decide which key function to use.

    Defaults to ``default_key_func``.
    """
    if key_func is not None:
        if callable(key_func):
            return key_func
        else:
            return import_string(key_func)
    return default_key_func

def get_connection(backend=None, fail_silently=False, **kwds):
    """Load an email backend and return an instance of it.

    If backend is None (default) settings.EMAIL_BACKEND is used.

    Both fail_silently and other keyword arguments are used in the
    constructor of the backend.
    """
    klass = import_string(backend or settings.EMAIL_BACKEND)
    return klass(fail_silently=fail_silently, **kwds)

def get_password_validators(validator_config):
    validators = []
    for validator in validator_config:
        try:
            klass = import_string(validator['NAME'])
        except ImportError:
            msg = "The module in NAME could not be imported: %s. Check your AUTH_PASSWORD_VALIDATORS setting."
            raise ImproperlyConfigured(msg % validator['NAME'])
        validators.append(klass(**validator.get('OPTIONS', {})))

    return validators

def get_hashers():
    hashers = []
    for hasher_path in settings.PASSWORD_HASHERS:
        hasher_cls = import_string(hasher_path)
        hasher = hasher_cls()
        if not getattr(hasher, 'algorithm'):
            raise ImproperlyConfigured("hasher doesn't specify an "
                                       "algorithm name: %s" % hasher_path)
        hashers.append(hasher)
    return hashers

def load_backend(path):
    return import_string(path)()