v4.9.0

Features

• Parameter.consume_multiple now accepts int or tuple[int, int] for min/max element bounds.

  • An int sets a minimum (e.g. consume_multiple=2 requires at least 2 values).
  • A tuple sets both bounds (e.g. consume_multiple=(1, 3) requires 1–3 values).
  • Violations raise ConsumeMultipleError.

  # Require 1–3 space-separated values: --files a.txt b.txt c.txt
  files: Annotated[list[str], Parameter(consume_multiple=(1, 3))]

  By @BrianPugh in #764

• New field Parameter.allow_repeating controls whether an option can be specified multiple times.

  • False raises RepeatArgumentError on repeat (useful with consume_multiple).
  • True allows repeats for any type; scalars use last-wins semantics.
  • None (default) preserves existing behavior: lists accumulate, scalars error.

  # Allow --files a b c, but not --files a --files b
  files: Annotated[list[str], Parameter(consume_multiple=True, allow_repeating=False)]
  # Last value wins: --color red --color blue → "blue"
  color: Annotated[str, Parameter(allow_repeating=True)]

  By @BrianPugh in #768

• New field App.help_prologue displays text before the "Usage" line in help output.
  Inherited by subcommands; override per-command or set to "" to disable.

  app = App(help_prologue="myapp v1.0.0 — https://example.com")

  By @tahv in #769

Bug Fixes

• Positional-only list parameters no longer consume tokens that appear after interleaved keyword arguments. a b --bar 8 d now correctly errors instead of silently assigning d to the positional list. By @BrianPugh in #766

Other

• Added contributing guide. By @BrianPugh in #767

New Contributors

• @tahv made their first contribution in #769

Full Changelog: v4.8.0...v4.9.0