On 9/2/2017 6:53 AM, Steve D'Aprano wrote:
I want to delay a computation and then print it, in the REPL (interactive
interpreter). I have something like this:
import time
from threading import Timer
def do_work():
x = 2 + 2
print("It is", time.asctime(), "and 2+2 is", x)
def schedule_work():
Timer(60, do_work, ()).start() # schedule it in one minute
Is this the right way to do it?
If I do that, it works, mostly. For example:
py> schedule_work()
py> dir(45) # do other stuff, in the interactive interpreter, for one minute
['bit_length', 'conjugate', 'denominator', 'from_bytes', 'imag', 'numerator',
'real', 'to_bytes']
py>
py> It is Sat Sep 2 20:37:58 2017 and 2+2 is 4
The problem is that after the message is printed, the REPL's prompt is
disrupted. This is especially annoying when I'm in the middle of typing a line.
This is just a cosmetic flaw, but it would be nice if I could tell Python to
redraw the current line. For example, using _ to indicate the position of the
cursor, this is what happens now:
py> class K:
... attribute =It is Sat Sep 2 20:48:39 2017 and 2+2 is 4
_
This is what I'd prefer:
py> class K:
... attribute =It is Sat Sep 2 20:48:39 2017 and 2+2 is 4
... attribute =_
I loaded your code into IDLE editor, hit F5, then interactively in Shell:
>>> schedule_work()
>>> It is Sat Sep 2 19:13:44 2017 and 2+2 is 4
"thei is kjlkj jjdkj f jkjkd j"
'thei is kjlkj jjdkj f jkjkd j'
With a 10sec delay, I was near the end of typing the statement after the
prompt. When the print came, the partial entry was pushed down to a new
line. I think that this is even better than what you asked for. I
closed the string and hit return and got the normal echo.
If one is entering a multiple line statement, the whole statement is
pushed down.
>>> go()
>>> It is Sat Sep 2 19:42:10 2017 and 2+2 is 4
a = (
12,
IDLE usually keeps input blocks, output blocks, and error blocks
separated, on separate lines. Response to input(prompt) is an
exception. There is also an ocassional bug that I cannot reproduce yet.
I consider not moving the prompt down a minor bug.
bugs.python.org/issue31331
The other problem is that if I exit the REPL while a Timer is still active, it
freezes until the time has run before exiting. I know you can't kill a thread
from the main thread, but is there a way for the Timer to see that the
interpreter is shutting down and shut itself down?
If you kill a process from another process, it should die. It does with
your code run from IDLE.
On Windows, the background user-code execution process start at 11.x Mb.
In Win 10 task manager, background processes are listed separately
from app windows. I restored 60 sec delay and added s = 'a'*10000000
near the top of your code to differentiate a process with your code from
the default user process.
======================= RESTART: F:\Python\mypy\tem.py
=======================
>>> schedule_work()
>>> # Hit Restart Shell
=============================== RESTART: Shell
===============================
>>>
Restart Shell means kill the current user process and start a new one.
Watching TackManager while doing so, the 20+Mb process is immediately
replaced by a default 10+Mb process. Closing Shell justs kills the
20+Mb process.
--
Terry Jan Reedy
--
https://mail.python.org/mailman/listinfo/python-list
