Ignoring arguments

There may be cases in which a user wants to provide certain arguments on the command line that $λ should ignore (not return in the output of Parser.parse_args or pass to the a decorated function). Suppose we wish to ignore any arguments starting with the --config- prefix:

>>> from dollar_lambda import flag, option
>>> regex = r"config-\S*"
>>> config_parsers = flag(regex) | option(regex)

In the case of ordered arguments, we simply use the ignore method:

>>> p = flag("x") >> config_parsers.ignore() >> flag("y")

This will ignore any argument that starts with --config- and comes between x and y:

>>> p.parse_args("-x", "-config-foo", "-y")
{'x': True, 'y': True}

Because of the way we defined config_parsers, this also works with option:

>>> p.parse_args("-x", "-config-bar", "1", "-y")
{'x': True, 'y': True}

In the case of nonpositional, @command, @parser, and CommandTree, use the repeated keyword:

lower-level syntax@command syntax

>>> from dollar_lambda import nonpositional
>>> p = nonpositional(flag("x"), flag("y"), repeated=config_parsers.ignore())

Now neither config-foo nor config-bar show up in the output:

lower-level syntax@command syntax

>>> p.parse_args("-x", "-y", "-config-foo", "-config-bar", "1")
{'x': True, 'y': True}

This works regardless of order:

lower-level syntax@command syntax

>>> p.parse_args("-config-baz", "1", "-y", "-config-foz", "-x")
{'y': True, 'x': True}

And no matter how many matches are found:

lower-level syntax@command syntax

>>> p.parse_args(
...     "-config-foo",
...     "1",
...     "-config-bar",
...     "-y",
...     "-config-baz",
...     "2",
...     "-x",
...     "-config-foz",
... )
{'y': True, 'x': True}