How can I type hint a variable that might contain a literal class

Question

I'm adding some type hints to a stub of vertica_python . One of the functions internally accepts the following parameter ( cursor_type ):

def row_formatter(self, row_data):
    if self.cursor_type is None:
        return self.format_row_as_array(row_data)
    elif self.cursor_type in (list, 'list'):
        return self.format_row_as_array(row_data)
    elif self.cursor_type in (dict, 'dict'):
        return self.format_row_as_dict(row_data)
    else:
        raise TypeError('Unrecognized cursor_type: {0}'.format(self.cursor_type))

So this function expects 'list', 'dict', the type list or type dict. I would like to use Optional[Literal[list, dict, 'list', 'dict']], but this is not supported:

Type arguments for "Literal" must be None, a literal value (int, bool, str, or bytes), or an enum value

Is there any way to achieve what I am trying?

Answer 1

You can type hint it as Union[None, Type[list], Type[dict], Literal["list", "dict"]]

(import Union and Type from typing)

Just watch out, as this would also accept a subclass of list or dict