Develop Reference

How to thread two functions where one output effect the others actions

Here's my code:
import time
import keyboard #pip install keyboard - could use pynput listener instead.
from threading import Thread
hshtag = int(0)
done = False
fire = False
def StopStart(fire):
while not done:
global fire
if keyboard.is_pressed('#'):
hshtag = hshtag + 1
if hshtag % 2 ==0:
fire = False
else:
fire = True
return fire
def NormalFire():
while not done:
global fire
if fire == True:
#do x
else:
pass
t1 = Thread(target = StopStart)
t2 = Thread(target = NormalFire(fire))
t1.start()
t2.start()
The problem is function StopStart (should) effect what function Normalfire does but as the function only accepts a value for fire when it starts running (so it doesn't work). What I want is change what function normalfire does with function stopstart. and if you're wondering why I am using threading it because '#do x' actually takes a while to work so as one continuous script if I clicked hash at the wrong time it wouldn't stop. Maybe I could do this with classes instead but im not good with classes so if someone could either help with that or fix the above code that would be great thanks.
New attempt at explaining what's wrong with the top code - Ok, so both functions should be running simultaneously (which they are) - so no problems there. but as the function StopStart changes the boolean fire to true/false I want that to cause my NormalFire function to change what it is doing - nothing when I haven't clicked hash yet and something if I've clicked hash once but if I then click hash while its running it will finish whats its running then do nothing waiting for hash to be clicked again.
Sorry, my question wasn't clear take this code as a simplification of my core question.
##imports
import time
import keyboard #pip install keyboard - could use pynput listener instead.
from threading import Thread
##variable assigning
hshtag = int(0)
done = False
fire = False
def x():
while not done:
fire = True
return fire
def y(fire):
while not done:
if fire:
print('ok')
else:
pass
t1 = Thread(target = x)
t2 = Thread(target = y(fire))
t1.start()
t2.start()
Currently, the above code outputs nothing even though I've set 'fire = true' in function x and returned it how would I edit this code so that when boolean fire changes to true the function y starts printing ok?
Editing like Nair suggested also returns nothing and after 15 second the program stops running edited code:
##imports
import time
import keyboard #pip install keyboard - could use pynput listener instead.
from threading import Thread
##variable assigning
hshtag = int(0)
done = False
fire = False
def StopStart():
while not done:
fire = True
return fire
def NormalFire():
while not done:
if fire:
print('ok')
else:
pass
t1 = Thread(target = StopStart)
t2 = Thread(target = NormalFire)
t1.start()
t2.start()

I'm unable to comment so I apologize in advanced. I'm having trouble understanding your question above, but I reworked your code - fix/add whatever you need and get back to me!
import time
import keyboard #pip install keyboard - could use pynput listener instead.
from threading import Thread
hshtag = int(0)
done = False
fire = False
def StopStart():
while not done:
# global fire - You're setting StopStart up for a param that needs passed, that also is named another variable
# So it will just over write it (Also, no arg is passed for StopStart(fire))
if keyboard.is_pressed('#'):
hshtag = hshtag + 1
if hshtag % 2 == 0 : fire = False
else : fire = true
return fire
def NormalFire():
while not done:
#global fire - Don't need to global it, you would've had to global done if that was the case
if fire: # don't need == true, just need if fire (if true)
print("x")
t1 = Thread(target=StopStart)
t2 = Thread(target=NormalFire)
t1.start()
t2.start()

Not sure that this is exactly what you're asking for. I would maybe listen for keyboard events outside of either thread. Instead, just bind keyboard events to a callback which set a threading.Event object. Sorry for the weird and slightly morbid example:
from pynput import keyboard
from threading import Thread, Event
plate_dropped = Event()
def on_press(key):
if key is keyboard.Key.enter:
plate_dropped.set()
listener = keyboard.Listener(on_press=on_press)
def poll_plate_status():
from time import sleep
from random import choice
messages = [
"It sure is tempting, eh?",
"Are you gonna do it?"
]
print("It'd be a shame if someone would drop this plate and scare grandpa!")
while not plate_dropped.is_set():
print(choice(messages))
sleep(0.5)
print("The plate has been dropped!")
def poll_grandpa_status():
from time import sleep
from random import choice
messages = [
"*zzzZZZzzz*",
"*Snoooreee*"
]
print("Grandpa is sound asleep.")
while not plate_dropped.is_set():
print(choice(messages))
sleep(0.5)
print("HUH!?")
plate_thread = Thread(target=poll_plate_status, daemon=True)
grandpa_thread = Thread(target=poll_grandpa_status, daemon=True)
plate_thread.start()
grandpa_thread.start()
listener.start()

##imports
import time
import keyboard #pip install keyboard - could use pynput listener instead.
from threading import Thread
##variable assigning
hshtag = int(0)
done = False
fire = False
def StopStart(self, interval=1):
hshtag = 0
self.interval = interval
while not done:
if keyboard.is_pressed('#'):
hshtag = hshtag + 1
if hshtag % 2 ==0:
fire = False
else:
fire = True
def NormalFire():
while not done:
print('NormalFire Runs')
time.sleep(1)
if fire:
print('*fires*')
else:
print('*does nothing*')
#t1 = Thread(target = StopStart, daemon=True)
t2 = Thread(target = NormalFire, daemon=True)
#t1.start()
t2.start()
while not done:
#time.sleep()
if keyboard.is_pressed('#'):
hshtag = hshtag + 1
time.sleep(0.1)
if hshtag % 2 ==0:
fire = False
print(fire)
else:
fire = True
print(fire)
I realised my problem was my ides of threading (im new to it) this achieves what I wanted thanks for all the help.

How to make a loop that calculates running time?

I'm making a simple client/server program in Python 3 and in the client I would like a clock or printout of the running time. I'm trying to make it in a loop that starts at the beginning of the program, but in a thread so the rest of the code keeps going.
class time_thread():
def run(self):
loop = 0
while (zetime > -1):
print(zetime);
zetime = zetime + 1;
time_thread.start()
zetime = 0
This is what I have so far, but it doesn't work. It says:
time_thread has no attribute start()
I'm new to this and haven't used threads before, so I'm not sure how to go about this. Is there a better way?

I think this is what you're looking for:
import time, sys
zetime = 0
while (zetime > -1):
sys.stdout.write("\r" + str(zetime))
sys.stdout.flush()
time.sleep(1)
zetime = zetime + 1;

First of all , to use Thread module, you have to inherit the class Thread on your class, so you can use their methods like start.
To calculate time, you can use datetime.
from datetime import datetime
from time import sleep
start_time = datetime.now()
sleep(5) # code that you want to calculate.
end_time = datetime.now()
print(end_time - start_time)
Just place this

So let's say you define a function elapsed_time such as:
import time, sys
def elapsed_time(time_start):
''' time_start: a time.time()
Goal: print the elapsed time since time_start '''
# Allow to stop the counting once bool_time = False in the main program
global bool_elapsed_time
# loop while the condition
while bool_elapsed_time == True:
# Note: erase and write below does not work in spyder but in a shell yes
print ("Elapsed time: {} seconds".format(int(time.time() - time_start))),
sys.stdout.flush()
print ("\r"),
time.sleep(1)
# erase the line with elapsed time to clean the shell at the end
sys.stdout.flush()
print ("\r"),
Then in your program:
import threading
bool_elapsed_time = True
t = threading.Thread(name='child procs', target=elapsed_time, args=(time.time(),))
t.start()
## Here add the job you want to do as an example:
time.sleep(10)
bool_elapsed_time = False #to stop the elapsed time printing
Should do the job you want to do.
Note: I used python 2.7 so it might be slightly different with 3.x

Python: How to start/stop while True loop on Keyboard event

I am trying to write a little script that emulates mouse-clicking. It should start/stop when a combination of keys is pressed on the keyboard, so I figured every time this combination is pressed I would spawn or terminate a child process that just contains a while True loop and does some clicking. Now I can get the loop to start, but not to terminate. I tried creating a new process just for the HookManager, but i got the same results. Any help with this would be very appreciated
import time
import win32api
import win32con
import pythoncom
import pyHook
import multiprocessing
i=0
def click():
while True:
win32api.mouse_event(win32con.MOUSEEVENTF_LEFTDOWN,0,0)
win32api.mouse_event(win32con.MOUSEEVENTF_LEFTUP,0,0)
time.sleep(0.005)
def OnKeyboardEvent(event):
global i
if (event.Ascii == 4) and (i == 0):
i = 1
c = multiprocessing.Process(target=click())
c.start()
print("started")
elif (event.Ascii == 4) and (i == 1):
i = 0
c.terminate()
print("terminated")
return True
hm = pyHook.HookManager()
hm.KeyDown = OnKeyboardEvent
hm.HookKeyboard()
pythoncom.PumpMessages()

Obviously you dont want to use while True: statement, but something like this:
def worker():
while running:
#do the work
...
def terminateWorker():
running = false
...
running = true
startWorker()
terminateWorker()

Or you can use break in if statement checking loop stop flag.
def click():
while True:
if(stopNow):break
...
stopNow=false

python add time to a countdown already running

I want to have an app where if I click a button I add X amount of time to my running countdown timer.
I'm guessing I have to use threads for this but am not sure how to implement it..
Here is the code I have so far:
def countdown_controller(add_time):
end_it = False
def timer(time_this):
start = time.time()
lastprinted = 0
finish = start + time_this
while time.time() < finish:
now = int(time.time())
if now != lastprinted:
time_left = int(finish - now)
print time_left
lastprinted = now
if end_it == True:
now = finish
time.sleep(0.1)
# Check if the counter is running otherwise just add time.
try:
time_left
except NameError:
timer(add_time)
else:
if time_left == 0:
timer(add_time)
else:
add_this = time_left
end_it = True
while now != finish:
time.sleep(0.1)
timer(add_time + add_this)
Obviously this will not work, because every time I call countdown_controller(15) fx, it will start counting down for 15 seconds and if I click my button nothing happens until the timer is ended.
Help would be greatly appreciated.

I would say that there is a flaw in the design of the code, because your screen output blocks down the entire program doing nothing (time.sleep(0.1)).
Typically what you want to to do in these cases is having a main loop in your program that cycles through the various operations that make your program run. This guarantees a sensible distribution of system resources between the various tasks.
In your specific case, what you would like to have in your main loop is:
Check user input (has extra time been added?)
Update output of the countdown
Example implementation:
import time
import curses
# The timer class
class Timer():
def __init__(self):
self.target = time.time() + 5
def add_five(self):
self.target += 5
def get_left(self):
return int(self.target-time.time())
# The main program
t = Timer()
stdscr = curses.initscr()
stdscr.nodelay(True)
curses.noecho()
# This is the main loop done in curses, but you can implement it with
# a GUI toolkit or any other method you wish.
while True:
left = t.get_left()
if left <= 0:
break
stdscr.addstr(0, 0, 'Seconds left: %s ' % str(left).zfill(3))
c = stdscr.getch()
if c == ord('x') :
t.add_five()
# Final operations start here
stdscr.keypad(0)
curses.echo()
curses.endwin()
print '\nTime is up!\n'
The above program will increase the counter of 5 seconds if you press the x key (lowercase). Most of the code is boilerplate to use the curses module, but of course if you use PyGTK, PySide or any other graphical toolkit, it will be different.
EDIT: As a rule of thumb, in python you want to avoid threading as much as you can, both because it often (but not always) slows down programs (see "Global Interpreter Lock") and because it makes software harder to debug/maintain.
HTH!

I would probably have a Timer object with a finish attribute that I could simply add an int to. Have that timer running in another thread that you can then query for the current time remaining from your GUI.
class Timer(object):
def __init__(self, length):
self.finish = time.time() + length
def get_time(self):
return time.time() >= self.finish

pyHook + pythoncom stop working after too much keys pressed [Python]

this is my script:
import pyHook
import pythoncom
hookManager = pyHook.HookManager()
def onKeyboardEvent(event):
if event.KeyID == 113: # F2
#do something#
return True
hookManager.KeyDown = onKeyboardEvent
hookManager.HookKeyboard()
pythoncom.PumpMessages()
after the key specified on the keyboard event, or the F2 key as my script, is pressed for several times, the script stop working...
Anyone knows why? or how to solve it?
I have to restart the script every time this happens, and I have to press the key a lot in my script...

Maybe you can call the function as a Thread to execute asynchronously, add them to your own queue or set a condition to not execute if it's already running, that will stop filling the messagepump which is that is failing.
Option 1. This will add the function execution to the threads queue:
import pythoncom, pyHook, threading
lock = threading.Lock()
def myFunc(i):
lock.acquire() #execute next function until previous has finished
#some code
lock.release()
def OnKeyboardEvent(event):
keyPressed = chr(event.Ascii)
if keyPressed == 'z':
t = threading.Thread(target=myFunc, args=(1,)) #added to queue
t.start()
return True
hm = pyHook.HookManager()
hm.KeyDown = OnKeyboardEvent
hm.HookKeyboard()
pythoncom.PumpMessages()
Option 2. or this will ignore other processing calls if it's busy:
def myFunc(i):
myFunc.isRunning = True
#some code
myFunc.isRunning = False
myFunc.isRunning = False
def OnKeyboardEvent(event):
keyPressed = chr(event.Ascii)
if keyPressed == 'z':
if not myFunc.isRunning: #if function is being executed ignore this call
t = threading.Thread(target=myFunc,args=(1,))
t.start()
return True
of course you should be careful when you add code by capturing exceptions or the thread will stay blocked.