Python and nesting classes for structure

Question

I am having a bit of trouble with nesting classes in python.

Mind you my code below is a simplified example showing what I want to do, but basically I want to use nested classes to make my code more structured and make sure I don't run into name clashes for certain functions.

See here my example code:

class Chrome:
 def __init__(self, url='http://localhost:4723/wd/hub'):
 # Capabilities
 capabilities = Capabilities.chrome()
 # Start session
 self.driver = webdriver.Remote(url, capabilities)
 def get_url(self, url):
 # Go to URL
 self.driver.get(url)
 class actions:
 @staticmethod
 def browse_url(url):
 # Go to url
 Chrome.get_url(url)
if __name__ == '__main__':
 browser = Chrome()
 browser.actions.browse_url('https://www.google.com')

The goal as you can see in if __name__ == '__main__' is to be able to start a browser instance, and then call functions in a structured way.

However I have no clue on how to correctly achieve the browser.actions.browse_url('https://www.google.com') concept.

How is this done correctly ?

• kindall: What problem are you having? Error message? If so, what? Unexpected result? What are they?
• Snowlav: @kindall error: TypeError: unbound method get_url() must be called with Chrome instance as first argument (got str instance instead)

Answer 1

You should call get_url from an instance of Chrome and not the class itself, since it's an instance method and not a static one:

...
@staticmethod
def browse_url(url):
 Chrome().get_url(url) 
...
if __name__ == '__main__':
 Chrome.actions.browse_url('https://www.google.com')

• Snowlav: Wouldn't this create a new instance every time? That's what I want to avoid.
• Moses Koledoye: @Snowlav Yes it would. Except you make it a static method, and then you'll have to figure another way to set up a driver for the class that is accessible by get_url
• Snowlav: home can I share the same instance for every function then? I thought that's why I called browser = Chrome() at the start. I could say browser.get_url(url) in the function however that requires users to always use the variable browser to create the instance
• Moses Koledoye: Keep in mind that the action class is nested in the Chrome class and browse_url is static, so this makes it a little more complicated than you think
• Snowlav: I don't think it's possible at all.