Created
December 3, 2020 09:37
-
-
Save gaborbernat/67b653f1d3ce4857a065a3bd81e424df to your computer and use it in GitHub Desktop.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
"""The challenge here is to make grand children print out the value set by child, without access to modify cannot_modify""" | |
from threading import Thread, local, current_thread | |
# solution start | |
def new_start(self): # need to patch this | |
self.parent = current_thread().ident | |
old_start(self) | |
old_start, Thread.start = Thread.start, new_start | |
class Local(local): | |
threads = {} | |
def __init__(self): | |
parent = getattr(current_thread(), "parent", None) | |
self._update_thread_var(self.threads.get(parent, 'default')) | |
def _update_thread_var(self, value): | |
self._value = value | |
self.threads[current_thread().ident] = self._value | |
@property | |
def value(self): | |
return self._value | |
@value.setter | |
def value(self, value): | |
self._update_thread_var(value) | |
var = Local() | |
# solution end | |
def peek(from_name): | |
print(f"{from_name}: {var.value}\n", end="") | |
def master(): | |
var.value = "master" | |
peek("master") | |
children = [Thread(target=child, name=name, args=(name,)) for name in ("A", "B")] | |
[t.start() for t in children] | |
[t.join() for t in children] | |
def child(name): | |
var.value = name | |
peek(name) | |
cannot_modify(name) | |
def cannot_modify(name): | |
thread = Thread(target=grand_child, name=f"{name}-{0}", args=(f"{name}-{0}",)) | |
thread.start() | |
thread.join() | |
def grand_child(name): | |
peek(name) | |
master() | |
""" | |
master: master | |
A: A | |
A-0: A | |
B: B | |
B-0: B | |
""" |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment