Question

Basically I’m a C# developer,
I know the way C# does, EventHandler, delegate, even…

but whats the best way to implement it on Python.

Answer 1

I think you should be able to use a function:

def do_work_and_notify(on_done):
    // do work
    on_done()

def send_email_on_completion():
    email_send('[e-mail]', 'you are done')

do_work_and_notify(send_email_on_completion)

Functions (and even methods) in python are first-class objects that can be tossed around like anything else in the language.