Re: [BuildStream] bst CLI design and consistency (UI)

[Jürg Billeter <j bitron ch>]

Hi Richard,

On Thu, 2018-12-06 at 17:28 +0000, Richard Maw via BuildStream-list
wrote:
> On Wed, Dec 05, 2018 at 11:14:57AM +0100, Jürg Billeter wrote:
> > I'd like to avoid the need for `--command`. Command wrappers on UNIX
> > systems typically use `--` as separator where that's necessary. Is
> > there no way with `Click` we can support `--` between element arguments
> > and command?
> >
> > If `Click` has no built-in support for this, can't we do it ourselves,
> > i.e., declare a single `Click` argument list for both? I don't know
> > whether we can provide proper help/usage in that case, but worst case
> > we could still explain usage in the help text for that combined option.
> > And with mandatory .bst extensions, we could even make `--` optional.
>
> I looked at doing this before settling on the `-e` syntax.
>
> Click not only has no built-in support for this
> but obstructs us in attempting to do our own parsing
> by consuming the -- itself and having no facility for us to get it.
>
>     $ cat > test.py <<'EOF'
>     > import click
>     > 
>     > @click.command()
>     > @click.argument('args', nargs=-1)
>     > def main(args):
>     >     print(args)
>     > 
>     > if __name__ == '__main__':
>     >     main()
>     > EOF
>     $ python3 test.py foo bar -- baz qux
>     foo bar baz qux

We could disable `allow_interspersed_args` as I don't think we
need/want that anyway:

        import click

        @click.command(context_settings={"allow_interspersed_args": False})
        @click.argument('args', nargs=-1)
        def main(args):
            print(args)

        if __name__ == '__main__':
            main()

        $ python3 test.py foo bar -- baz qux
        ('foo', 'bar', '--', 'baz', 'qux')

Cheers,
Jürg