Displaying command alias in help/usage about picocli

[remkop]

Hi @roxspring thank you for raising this!

No you haven't overlooked anything, currently the help is the same regardless of which alias was used to invoke it.

Some thoughts:
Without looking at the code (on my phone now, working from memory) one part of the problem is that the parser doesn't keep track of which alias was actually used to trigger the help being displayed.

maincmd help subcmdAlias1
maincmd help subcmdAlias2

maincmd subcmdAlias1 --help
maincmd subcmdAlias2 -h

It may not be easy to build bookkeeping to keep track of this. Such bookkeeping also needs to handle scenarios like nested sub-subcommands and repeatable subcommands.

Secondly, the display part. Currently help is static: it's not designed to change depending on user input (only the error message is, but that isn't part of the usage help message).

There's no parser state available to the logic that constructs the usage help message. I imagine we would have to use a static variable (or something similar) to store the user-specified command name/alias, to make that alias available to the logic that constructs the usage help message. If you can think of a better solution, ideas are welcome!

Finally, the help is designed to be highly customizable. If applications have tests that assert the exact help message, then these tests may break, that's unavoidable.

But other than that, any changes we introduce here should not impact other applications who have customized their help message, those customizations should continue to work as before.

[remkop]

Reading the description for this ticket again it’s clear the alias is for a subcommand. Apologies, I didn’t read carefully.

I edited my previous comment.

[roxspring]

It may not be easy to build bookkeeping to keep track of this. Such bookkeeping also needs to handle scenarios like nested sub-subcommands and repeatable subcommands.

Looking at repeatable subcommands gave me the inspiration for #2105 - arguably a bit hacky so feedback welcome!