Use "ESC" key as abort

[juxeii]

In my use case it would be great if I could detect that the user has pressed ESCin select_multiple. Is this somehow possible?

[petereon]

I have just checked and ESC is accepted as an abort functionality in select_multiple on my Mac.

For keypress handling beaupy uses python_yakh under the hood which tries to abstract the platform layer as much as possible but I am sure there are some hiccups still.

Could you please elaborate in terms of your platform and terminal emulator?

Further, if you wouldn't mind testing this for me, you could run this script and press ESC while it's running and post the resulting prints here.

from yakh import get_key

key = get_key()
print(key.key_codes)
print(bytes(key.key, 'utf-8'))
print(key.is_printable)

yakh is a dependency of beaupy so as long as you run this in the same virtual env you run beaupy in, it should work.

[juxeii]

I am on 08:20 $ cat /etc/os-release

NAME="Red Hat Enterprise Linux Server"
VERSION="7.9 (Maipo)"
ID="rhel"
ID_LIKE="fedora"
VARIANT="Server"
VARIANT_ID="server"
VERSION_ID="7.9"
PRETTY_NAME="Red Hat Enterprise Linux Server 7.9 (Maipo)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:redhat:enterprise_linux:7.9:GA:server"
HOME_URL="https://www.redhat.com/"
BUG_REPORT_URL="https://bugzilla.redhat.com/"

REDHAT_BUGZILLA_PRODUCT="Red Hat Enterprise Linux 7"
REDHAT_BUGZILLA_PRODUCT_VERSION=7.9
REDHAT_SUPPORT_PRODUCT="Red Hat Enterprise Linux"
REDHAT_SUPPORT_PRODUCT_VERSION="7.9"

Running your snippets yields

(snaputils-i_jQa2nS-py3.9) ✔ .../coredev [main ↑·1|✚ 7⚑ 22] 
08:22 $ /home/user/.cache/pypoetry/virtualenvs/snaputils-i_jQa2nS-py3.9/bin/python /test/playground.py
(27,)
b'\x1b'
False

I need do distinguish between ENTERand ESC, which both yield no selection on my side. But "Enter" should mean no selection and ESCshould mean abort all together.

[petereon]

I see, would raising a KeyboardInterrupt on escape and handling it yourself be a good alternative?

If so, you could edit the global Config object, setting .raise_on_interrupt to True and additonally DefaultKeys object setting .escape to [] and appending Keys.ESC into .interrupt attribute.

Just for my reference, what exact behavior would you envision for ESC key? Should it raise some class of Exception?

[juxeii]

I am not a big fan of exceptions. Returning the last key pressed(as tuple element to the already existing return values) would be the most flexible I guess.

So I did

elif keypress in DefaultKeys.escape:
            if Config.raise_on_interrupt:
                raise KeyboardInterrupt()

which is OK for me. Is it also OK for you? Possible to release a patch version? I really think that ENTERand ESCshould have different semantics when the user selects nothing.

[petereon]

So I agree that ENTER and ESC might benefit from different semantics, but I don't want to be releasing breaking changes, so having the functions return tuples is not viable for me.

I would say my best option is actually going for a second config option which controls whether to raise an Exception on ESC key, defaulting to current behavior of not raising on ESC.

Coming from languages that have proper way to deal with nothingness I appreciate that exceptions are suboptiomal, but they are canonical in Python.

[juxeii]

Good point on breaking changes. You proposal sounds reasonable and it would be great if you could release this patch soon. Hope you have simple deploy scripts ;)

[petereon]

I should be able to get it out today, just much later, I am at work atm :sweat_smile:

[juxeii]

Me2 :) Thx for you prompt effort. I will close this issue.

[petereon]

Published: https://github.com/petereon/beaupy/releases/tag/v3.4.0

Should be on PyPI in few minutes.

[juxeii]

Works like a charm! Many thanks and keep up the good work :blush: