Programmatically exit the REPL

[Matthew Fitzgibbons]

I've got a pretty complex interactive command line program. Instead of
writing my own REPL, I'm using the Python interpreter (an infinitely
better solution). This program has two threads, a background thread and
the REPL thread. When you call quit() or sys.exit() in the REPL thread,
everything is perfectly happy. However, the background thread does some
long-running jobs, and I want it to have the ability to exit the program
when the job is complete. When I call quit() or sys.exit() from the
background thread, the REPL merrily continues on its way.

This is a very frustrating problem, so I'm hoping someone can shed some
light on it. Am I missing something simple? Or is this just impossible?
I don't see anything about breaking out of interact() in the code module
docs.


Here's a minimal example:

#!/usr/bin/env python -i
# You get the same behavior using code.interact()

import sys
import time
import threading

def end_the_program ():
# works if you call it from the REPL thread,
# but not the background thread
print "called end_the_program ()"
sys.exit()
# quit() # using quit() rather than sys.exit()
# results in identical behavior

keep_going = True
def runner():
while keep_going:
time.sleep(0.1)
end_the_program ()
threading.Threa d(target=runner ).start()

# end example


Here's the console session (edited for clarity):

Desktop$ ./exit_repl.py

>>keep_going = False

called end_the_program ()
# notice we didn't exit here

>>end_the_progr am()

called end_the_program ()
# but we did exit here
Desktop$


-Matt

[Alexander Schmolck]

Re: Programmaticall y exit the REPL

Without reading your post properly or having tried to do the same thing
myself: I think you might want to have a look at ipython; it gives a better
REPL and "embedding ipython" should give you plenty of hits as well.

Matthew Fitzgibbons <elessar@nienna .orgwrites:

I've got a pretty complex interactive command line program. Instead of writing
my own REPL, I'm using the Python interpreter (an infinitely better solution).
This program has two threads, a background thread and the REPL thread. When
you call quit() or sys.exit() in the REPL thread, everything is perfectly
happy. However, the background thread does some long-running jobs, and I want
it to have the ability to exit the program when the job is complete. When I
call quit() or sys.exit() from the background thread, the REPL merrily
continues on its way.
>
This is a very frustrating problem, so I'm hoping someone can shed some light
on it. Am I missing something simple? Or is this just impossible? I don't see
anything about breaking out of interact() in the code module docs.
>
>
Here's a minimal example:
>
#!/usr/bin/env python -i
# You get the same behavior using code.interact()
>
import sys
import time
import threading
>
def end_the_program ():
# works if you call it from the REPL thread,
# but not the background thread
print "called end_the_program ()"
sys.exit()
# quit() # using quit() rather than sys.exit()
# results in identical behavior
>
keep_going = True
def runner():
while keep_going:
time.sleep(0.1)
end_the_program ()
threading.Threa d(target=runner ).start()
>
# end example
>
>
Here's the console session (edited for clarity):
>
Desktop$ ./exit_repl.py

>>>keep_going = False

called end_the_program ()
# notice we didn't exit here

>>>end_the_prog ram()

called end_the_program ()
# but we did exit here
Desktop$
>
>
-Matt

--

[Matthew Fitzgibbons]

Re: Programmaticall y exit the REPL

Alexander Schmolck wrote:

Without reading your post properly or having tried to do the same thing
myself: I think you might want to have a look at ipython; it gives a better
REPL and "embedding ipython" should give you plenty of hits as well.
>

Thanks for the tip; I hadn't heard of ipython before. I will certainly
check it out. However, if anyone knows how to break out of the
interactive interpreter from another thread, I'd still very much like to
hear about it. :)

-Matt

[Matthew Fitzgibbons]

Re: Programmaticall y exit the REPL

Almar Klein wrote:

Hi,
>
If you insist on writing your own shell, you can also consider running
the commands in another python process.
I took the source code of Pype as an example, which uses a wx.Process.
I've tried the subprocess module as well, but could not get it to work.
>
Almar
>
2008/8/26 Matthew Fitzgibbons <elessar@nienna .org
<mailto:elessar @nienna.org>>
>
Alexander Schmolck wrote:
>
Without reading your post properly or having tried to do the
same thing
myself: I think you might want to have a look at ipython; it
gives a better
REPL and "embedding ipython" should give you plenty of hits as well.
>
>
Thanks for the tip; I hadn't heard of ipython before. I will
certainly check it out. However, if anyone knows how to break out of
the interactive interpreter from another thread, I'd still very much
like to hear about it. :)
>
>
-Matt
--

http://mail.python.org/mailman/listinfo/python-list

>
>

The whole point is that I *don't* want to write my own shell, I want to
use the Python interactive shell (iPython, while very neat, is overkill
for this purpose, and an extra dependency).

I use subprocess regularly, but it doesn't work in this case because (a)
the point of using an interactive interpreter is so that I can interact
with the job *while it's running* and (b) I *still* wouldn't be able
exit the interactive shell cleanly (I'd have to look up the PID and kill
it via the shell -- very ugly and not portable).

-Matt