resume execution after catching with an excepthook?

[Steven D'Aprano]

On Wed, 24 Oct 2012 13:51:30 +0100, andrea crotti wrote:

> So I would like to be able to ask for confirmation when I receive a C-c,
> and continue if the answer is "N/n".

I don't think there is any way to do this directly.

Without a try...except block, execution will cease after an exception is 
caught, even when using sys.excepthook. I don't believe that there is any 
way to jump back to the line of code that just failed (and why would you, 
it will just fail again) or the next line (which will likely fail because 
the previous line failed).

I think the only way you can do this is to write your own execution loop:

while True:
    try:
        run(next_command())
    except KeyboardInterrupt:
        if confirm_quit():
            break


Of course you need to make run() atomic, or use transactions that can be 
reverted or backed out of. How plausible this is depends on what you are 
trying to do -- Python's Ctrl-C is not really designed to be ignored.

Perhaps a better approach would be to treat Ctrl-C as an unconditional 
exit, and periodically poll the keyboard for another key press to use as 
a conditional exit. Here's a snippet of platform-specific code to get a 
key press:

http://code.activestate.com/recipes/577977

Note however that it blocks if there is no key press waiting.

I suspect that you may need a proper event loop, as provided by GUI 
frameworks, or curses.



-- 
Steven