Q:

How do you manage function scope and synchronization in Python 3

This a 2-question rolled into 1 - I get the following output from the script next
Checker: start of thread
Checker: ( 0 ) Hello, world
Checker: ( 1 ) Hello, world
Checker: ( 2 ) How do you do
Checker: ( 3 ) How do you do
Checker: start of thread
Checker: ( 4 ) Bye for now
Checker: exiting thread
Checker: ( 0 ) Bye for now
Checker: exiting thread

The script:
#!/usr/local/bin/python                                                                                                                           

import time
import threading

class CheckTscope:

def __init__ (self):
    self.name = 'checker'
    self.msg = None

def checker (self, msg="Hey stranger"):
    count = 0
    self.setMessage(msg)
    print ("Checker: start of thread")
    while True:
        time.sleep (0.04)
        print ("Checker: (", count, ")", self.getMessage())
        if self.carry_on:
            count += 1
            continue
        break
    print ("Checker: exiting thread")

def getMessage (self):
    return self.msg

def setMessage (self, text):
    self.msg = text

def construct (self, initxt):
    self.setMessage (initxt)
    self.carry_on = True
    reporter = threading.Thread(target=self.checker, args=(initxt,))
    reporter.start()

def destruct (self):
    self.carry_on = False

if __name__ == '__main__':
    ct = CheckTscope()
    ct.construct("Hello, world")
    time.sleep(0.125)
    ct.setMessage("How do you do")
    time.sleep(0.06)
    ct.destruct()
    time.sleep(0.02)
    ct.checker ("Bye for now")

The questions:

How can I make the function checker() accessible only to other functions in this class (limit the scope)?
How do I synchronize for multiple threads ("4 - Bye for now" is an error, counter should be reset when message is set to new value).

Essentially, I am looking for a replacement of "synchronized private void" from another language. Thank you for your help.

A:

1 - you dont. Scope of methods and variables is most of the time handled by programming conventions. In this case you would add a underline in the beggining of the checker to identify it as a private method that should only be called by the other methods inside the class.
2 - to synchronize multiple threads you need to work with the the threads using threading specific commands, trying to use the "carry_on" like you did will make you end in some weird alleys.
Ps: if I recall there is the @Async and @Sync annotations, you could look further into it.

