Answers

• Are environment valiables supported?

  Do it manually:

  cmd.bind(
      login=-option(
          "--password",
          default=os.environ.get("MY_PASSWORD"),
          help="Server password",
          show_default="Won't tell you !",
      )
  )
  

  Generally, environment variables should be treated as an external input and validated:

  def get_default_nthreads() -> int | None:
      try:
          val = int(os.environ["MYSERVER_NTHREADS"])
      except (ValueError, KeyError):
          return None
      return val if 0 < val < 100 else None
  
  cmd.bind(
      threads=-option("--threads", type=int, default=get_default_nthreads() or 4),
  )
  

• What about the bash autocompletion?

  Maybe someday.

• Where is the FileType with auto-opening?

  Use the pathlib.Path methods instead:

  def func(*, file: pathlib.Path):
      data=path.read_bytes()
  
  cmd.bind(file=option("--file", type=PathConv.file(exist=True)))
  

• May I use Enum as a type converter?

  StrEnum is nice and actually works.

  class MyEnum(StrEnum):
        A = "a"
        B = "b"
  
  def func(*, foo: MyEnum):
      pass
  
  Command(func).bind(
      foo=-option("--foo", type=MyEnum, choices=tuple(MyEnum))
  )
  

• Tell me more about this minus operator hack

  paramspecli abuses the ParamSpec:

  def func(*, port: int | None) -> None: ...
  
  cmd = Command(func)
  opt = option("--port", type=int)
  
  reveal_type(opt) # type is "Option[int, None]"
  reveal_type(-opt) # type is "int | None"
  
  reveal_type(cmd.bind) # type is "(*, port: int | None) -> None"
  cmd.bind(port=-opt) # typechecks ok!
  

  The negation operator is type-annotated as returning the Option's resulting type. Signatures match, type checker is happy. It's a lie - in runtime it's still the same Option class.

  class Option[T]:
  
      def __neg__() -> T:
          return self # type: ignore
  

  Minus is choosen as producing the minimum visual noise. Also it's a nod to the - options prefix character.

• Why such a stupid name?

  CLI libs should have cli in their name. It's the law. And clit is already taken on the PyPI.