Class CapturableArgumentParser

mypy/main.py:400–450

Override ArgumentParser methods that use sys.stdout/sys.stderr directly. This is needed because hijacking sys.std* is not thread-safe, yet output must be captured to properly support mypy.api.run.

class CapturableArgumentParser(argparse.ArgumentParser):
    """Override ArgumentParser methods that use sys.stdout/sys.stderr directly.

    This is needed because hijacking sys.std* is not thread-safe,
    yet output must be captured to properly support mypy.api.run.
    """

    def __init__(self, *args: Any, **kwargs: Any) -> None:
        self.stdout = kwargs.pop("stdout", sys.stdout)
        self.stderr = kwargs.pop("stderr", sys.stderr)
        super().__init__(*args, **kwargs)

    # =====================
    # Help-printing methods
    # =====================
    def print_usage(self, file: SupportsWrite[str] | None = None) -> None:
        if file is None:
            file = self.stdout
        self._print_message(self.format_usage(), file)

    def print_help(self, file: SupportsWrite[str] | None = None) -> None:
        if file is None:
            file = self.stdout
        self._print_message(self.format_help(), file)

    def _print_message(self, message: str, file: SupportsWrite[str] | None = None) -> None:
        if message:
            if file is None:
                file = self.stderr
            file.write(message)

    # ===============
    # Exiting methods
    # ===============
    def exit(self, status: int = 0, message: str | None = None) -> NoReturn:
        if message:
            self._print_message(message, self.stderr)
        sys.exit(status)

    def error(self, message: str) -> NoReturn:
        """error(message: string)

        Prints a usage message incorporating the message to stderr and
        exits.

        If you override this in a subclass, it should not return -- it
        should either exit or raise an exception.
        """
        self.print_usage(self.stderr)
        args = {"prog": self.prog, "message": message}
        self.exit(2, gettext("%(prog)s: error: %(message)s\n") % args)


class CapturableVersionAction(argparse.Action):