How to retrieve short/long option names (not values) of a parser?

[eugenesvk]

If I have

let overwrite = short('o').long("overwrite").help("Overwrite target file").switch();

How do I retrieve o and overwrite options (names, not values) at runtime, for example, to be able to print some error message to the user File exists, but overwrite flag isn't set, use '-o' or '--overwrite' so that in case I later change short('r') to something else I wouldn't have to update the text of the error message?

Thanks!

[pacak]

At the moment there's no easy way, I'd have them as const S_OVERWRITE: char = 'o'; and const L_OVERWRITE ... and use it both for the parser and for the error message.

Looking at hard ways - you can call overwrite.meta() and then recursively pattern match the result to get ShortLong that contains a visible names back. This will break once I publish a version I'm experimenting with now, but that version gives an easier way to access things.

[eugenesvk]

How would I get access to overwrite.meta() after I've used the combine! and .to_options()? OptionsParser doesn't seem to allow this, right?

meta seems to only be available to the Parser resulting from combine! before it's converted into runnable Options?

[pacak]

.meta() is accessible in any Parser, but not with OptionParser, right. .meta() will work though construct! just fine. If you have OptionParser - it will have all the options, not just overwrite. With OptionParser you could add some assertions (via completion mechanism, might require enabling) that flags -o and --overwrite are still present:

// assuming `options()` is your `OptionParser`
let r = options().run_inner(&Args::from(&["-o"]).set_comp(0)).unwrap_err().unwrap_stderr();
assert_eq!(r, "-o", "You need to update the error message");
let r = options().run_inner(&Args::from(&["--overwrite"]).set_comp(0)).unwrap_err().unwrap_stderr();
assert_eq!(r, "--overwrite", "You need to update the error message");

[eugenesvk]

But in the OptionParser case I wouldn't know what "-o" means, so it's not helpful to do the run_inner

Though actually that's the same issue with Parser.meta(): it has the flag names in the meta info, but doesn't include the struct field name (which is more permanent), so if in the future you add more conflicting options and reorder short/long options, you still wouldn't be able to auto-track which ones belong to the overwrite field

So I guess constants is indeed the only way now