Demonstration of Python threading library, specifically threading.Event class

threading_events.py

#!/usr/bin/python3
import threading

class FooBar:
    def __init__(self, n):
        self.n = n
        self.fooCanRun = threading.Event()
        self.barCanRun = threading.Event()
        
        self.fooCanRun.set()


    def foo(self, printFoo: 'Callable[[], None]') -> None:
        
        for i in range(self.n):
            
            if not self.fooCanRun.isSet():
                self.fooCanRun.wait()
            
            # printFoo() outputs "foo". Do not change or remove this line.
            printFoo()
            
            self.fooCanRun.clear()
            self.barCanRun.set()



    def bar(self, printBar: 'Callable[[], None]') -> None:
        
        for i in range(self.n):
            
            if not self.barCanRun.isSet():
                self.barCanRun.wait()
    
            # printBar() outputs "bar". Do not change or remove this line.
            printBar()
            
            self.barCanRun.clear()
            self.fooCanRun.set()