The "loop and a half"

[Steve D'Aprano]

On Sun, 8 Oct 2017 02:06 am, bartc wrote:

>> On 2017-10-07, bartc <bc at freeuk.com> wrote:
>> 
>>> Interactive Python requires quit() or exit(), complete with parentheses.
.......................^^^^^^^^^^^^^^^^^^^^^^^^^


>> Nonsense.  On Unix you can just press ctrl-D (or whatever you have
>> configured as eof) at the command prompt. On windows, it's Ctrl-Z
>> <Enter>.
> 
> Steve spoke about the 'usual quit/exit/bye' commands.

As well as Ctrl-D, EOF, which is a standard way to exit most Unix programs.

(Or as close as anything in Unix comes to a standard UI.)


> If you type 'quit' in interactive Python, then it says:
> 
>    Use quit() or Ctrl-Z plus Return to exit
> 
> Same for exit. So in Python, IF you want to use quit or exit to
> terminate, you have to use quit() or exit() instead.
> 
> So please explain how what I wrote was nonsense.

Do you still believe that quit/exit is REQUIRED?

To be pedantic, we have at least seven ways:

- EOF (Ctrl-D on Unix, Ctrl-Z ENTER on Windows);

- calling quit() or exit();

- raise SystemExit;

- call sys.exit()

- call os._exit();

- call os.abort();

- write your own custom quitter object that exits on simply being 
  printed, e.g.:

    class Bye:
        def __repr__(self):
            sys.exit(0)

    bye = Bye()

Four of these are intended for programmatic use, but they work interactively
as well. At least two of them shouldn't be used unless you know what you are
doing (os._exit and os.abort).


>>> Unless you've redefined quit and exit as something else, then you have
>>> to crash out by other means.)
>> 
>> Admit it, you're just trolling.
> 
> FFS, NOW what's wrong?

"Crash out".


> IF you DO redefine those names, then you DO have to use other means to
> terminate. I happen to call those means 'crashing out', because it's
> like yanking the plug rather than using the on/off switch.

os._exit and os.abort (especially the second) could legitimately be described
as "crashing out". The others, not within a million miles of it.


> Especially on 
> Windows where the usual Ctrl C doesn't work, so you resort to Ctrl-Break
> will which actually abort it. Ctrl Z is uncommon.

Thousands of Python programmers on Windows successfully learned to use Ctrl-Z
ENTER back in the days of Python 1.5, before quit/exit were added as a
convenience for beginners, and many of them probably still use it.

Yet again you assume that because YOU don't do something, nobody else in the
world could possibly do it.


> I'm getting fed up with this thread now.

This thread would be a lot less frustrating if you would enter into it with a
spirit of open-minded enquiry rather than an overbearing sense of superiority
that anything others do that you don't must be worthless.



-- 
Steve
“Cheer up,” they said, “things could be worse.” So I cheered up, and sure
enough, things got worse.