Add a option to help with --and-exit about dragon

[mwh]

This seems pretty reasonable. The goal is essentially that each entry can be dragged out once ("shelf"-style), and the program exits when there are no entries remaining?

I wonder whether this is severable into two parts:

1. Once-each mode, where an item is removed from the list once dragged out. Perhaps this is -1, --once-each.
2. Exit on empty, where the program closes once there are no entries left. Perhaps this is -X, --exit-empty. Arguably we could overload the existing -x with this meaning, but I imagine someone may have made a menu system or something out of it for which this would be a breaking change.

The mode you want would then be dragon -1 -X file.... A "shelf" mode, where it starts up and you can drag items in for temporary storage and back out at will, would be dragon -t -k -1 or something.

The shelf may be the only use for -1 without -X, however, so perhaps this is really two separate modes with some shared functionality: drag-and-remove until exhausted (your proposal), and drag-in-and-out-once (shelf). If there are other use cases for -1 or -X in the future it would be nice to have them, but I'm unsure whether there are other use cases or functionality where they make sense.

I know there are some others who watch these issues, so they might have comments on that. If you've already implemented this, however, I guess my question is: how straightforward is it to separate those two aspects? The functionality you describe sounds valuable already.

[DevHyperCoder]

The goal is essentially that each entry can be dragged out once ("shelf"-style), and the program exits when there are no entries remaining?

Exactly that!

Perhaps this is -X, --exit-empty. Arguably we could overload the existing -x with this meaning, but I imagine someone may have made a menu system or something out of it for which this would be a breaking change.

A new flag would be better so as to not break backwards-compatibility

I will make a PR with what I have done already. I don't know much of C, so there might be better ways to do it. If there are, please point them out and I will be more than happy to correct them.

adding a once-each to my existing solution seems to be quite straight forward.