How should I write the hints of variable type when there are multiple variable types or classes accepted in python? [duplicate]

Question

I want to make use of the hint (or maybe also called annotation?) of python to make easier my coding getting the functions of a class. Therefore I was using something like the following:

def convert_to_string(my_integer_number: int) -> str:
   return str(my_integer_number)

But now I'm working with selenium and I have multiple classes that can be accepted for the same code, for example:

import webdriver

def get_driver(browser = DEFAULT_BROWSER, headless=False) -> \
                         webdriver.Chrome or webdriver.Firefox or webdriver.Edge:
    """
    Returns a selenium webdriver:
    * browser: Available options are 'chrome', 'edge' and 'firefox'
    """
    if browser == 'chrome':
        return webdriver.Chrome(
            #....
        )
    
    if browser == 'firefox':
        return webdriver.Firefox(
            ...
        )

    if browser == 'edge':
        return webdriver.Edge(
            ...
        )

And then in the functions where make use of one of the returned drivers:

def access_login_page(driver: webdriver.Chrome or webdriver.Firefox or webdriver.Edge) -> None:
    """
    Access the login page using the header menu
    """
    ELEMENT_ID = 'header-sign-in'
    try:
        element: WebElement = WebDriverWait(driver, timeout=30).until(
            EC.element_to_be_clickable((By.ID, ELEMENT_ID))
        )

This looks like a lot of overhead but at the same time I find really usefull to have this information. Is this the correct approach to do this?

Answer 1

Use the typing module:

from typing import Union
import webdriver
...
def get_driver(browser = DEFAULT_BROWSER, headless=False) -> \
                         Union[webdriver.Chrome, webdriver.Firefox, webdriver.Edge]:
    ...

The typing module contains thin wrappers for built-in types and also things like Optional[<type>] (which is basically Union[<type>, None]), Any, Callable, etc.