The code below is for cross-platform prompting with input() once with
timeout. On timeout it will ask the user to press Enter so the prompter-
thread can shut down cleanly.
Removing the parts affecting _prompter_exit would allow resuming on timeout without the need for the user to hit Enter, at the cost of keeping the prompter-thread alive until the whole process exits.
Just joining a prompting thread with timeout like @Mad Physicist suggested would not work, since it doesn't unblock the input() call itself. Without using OS-specific libraries, there is (AFAIK) no way of waking up a thread waiting on input() without eventually providing some form of input.
The code is a boiled down version of my answer allowing multiple inputs within a given time span:
Taking in multiple inputs for a fixed time in Python
from threading import Thread, enumerate, Event
from queue import Queue, Empty
import time
SENTINEL = None
class PromptManager(Thread):
def __init__(self, timeout):
super().__init__()
self.timeout = timeout
self._in_queue = Queue()
self._out_queue = Queue()
self.prompter = Thread(target=self._prompter, daemon=True)
self._prompter_exit = Event()
def run(self):
"""Run worker-thread. Start prompt-thread, fetch passed
input from in_queue and forward it to `._poll()` in MainThread.
If timeout occurs before user-input, enqueue SENTINEL to
unblock `.get()` in `._poll()`.
"""
self.prompter.start()
try:
txt = self._in_queue.get(timeout=self.timeout)
except Empty:
self._out_queue.put(SENTINEL)
print(f"\n[{time.ctime()}] Please press Enter to continue.")
# without usage of _prompter_exit() and Enter, the
# prompt-thread would stay alive until the whole program ends
self._prompter_exit.wait()
else:
self._out_queue.put(txt)
def start(self):
"""Start manager-thread."""
super().start()
return self._poll()
def _prompter(self):
"""Prompting target function for execution in prompter-thread."""
self._in_queue.put(input(f"[{time.ctime()}] >$ "))
self._prompter_exit.set()
def _poll(self):
"""Get forwarded inputs from the manager-thread executing `run()`
and process them in the parent-thread.
"""
msg = self._out_queue.get()
self.join()
return msg
For Demonstration:
if __name__ == '__main__':
pm = PromptManager(timeout=5)
msg = pm.start()
print(f"User input: {msg}")
for i in range(3):
print(f"[{time.ctime()}] Do something else. "
f"Alive threads:{[t.name for t in enumerate()]}")
time.sleep(1)
Run with triggering timeout:
[Tue Nov 26 20:50:47 2019] >$
[Tue Nov 26 20:50:52 2019] Please press Enter to continue.
User input: None
[Tue Nov 26 20:50:57 2019] Do something else. Alive threads:['MainThread']
[Tue Nov 26 20:50:58 2019] Do something else. Alive threads:['MainThread']
[Tue Nov 26 20:50:59 2019] Do something else. Alive threads:['MainThread']
Process finished with exit code 0
Run with user input in time:
[Tue Nov 26 20:51:16 2019] >$ Hello
User input: Hello
[Tue Nov 26 20:51:19 2019] Do something else. Alive threads:['MainThread']
[Tue Nov 26 20:51:20 2019] Do something else. Alive threads:['MainThread']
[Tue Nov 26 20:51:21 2019] Do something else. Alive threads:['MainThread']
Process finished with exit code 0
