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command

Functions:

  • command_line

    Parses command-line arguments to manage kernel specs and start kernels.

command_line

command_line() -> None

Parses command-line arguments to manage kernel specs and start kernels.

This function uses argparse to handle command-line arguments for various kernel operations, including:

  • Starting a kernel with a specified connection file.
  • Adding a new kernel specification.
  • Removing an existing kernel specification.
  • Print version.

The function determines the appropriate action based on the provided arguments and either starts a kernel, adds a kernel spec, or removes a kernel spec. If no connection file is provided and no other action is specified, it prints the help message.

When starting a kernel, it imports the specified kernel factory (or uses the default Kernel class) and configures the kernel instance with the provided arguments. It then starts the kernel within an anyio context, handling keyboard interrupts and other exceptions.

Raises:

  • SystemExit

    If an error occurs during kernel execution or if the program is interrupted.

Source code in src/async_kernel/command.py
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def command_line() -> None:
    """
    Parses command-line arguments to manage kernel specs and start kernels.

    This function uses `argparse` to handle command-line arguments for
    various kernel operations, including:

    - Starting a kernel with a specified connection file.
    - Adding a new kernel specification.
    - Removing an existing kernel specification.
    - Print version.

    The function determines the appropriate action based on the provided
    arguments and either starts a kernel, adds a kernel spec, or removes
    a kernel spec.  If no connection file is provided and no other action
    is specified, it prints the help message.

    When starting a kernel, it imports the specified kernel factory (or uses
    the default `Kernel` class) and configures the kernel instance with
    the provided arguments. It then starts the kernel within an `anyio`
    context, handling keyboard interrupts and other exceptions.

    Raises:
        SystemExit: If an error occurs during kernel execution or if the
            program is interrupted.
    """

    class Mode(StrEnum):
        install = "install"
        uninstall = "uninstall"
        version = "version"
        help_all = "help_all"
        help = "help"
        start = "start"
        list = "list"
        show_config = "show_config"
        show_config_json = "show_config_json"

    description = """

Online Help: https://fleming79.github.io/async-kernel/latest/usage/commands/

Commands:
    - start: Start a kernel - configuration options are used when starting the kernel.
    - install: Install a kernelsepc - configuration options are stored in the kernel spec.
    - uninstall: Uninstall a kernelspec.

Tips:
    - Pass the flag '--user' to install/uninstall using the user profile. 
    - See `--help-all` for all configuration options available.
    - When starting from command line, add `--log-level=INFO` to show logged output. 
"""
    epilog = ""

    parser = argparse.ArgumentParser(
        prog="async-kernel",
        # usage="async-kernel <optional command> options ...",
        description=description,
        epilog=epilog,
        formatter_class=argparse.RawDescriptionHelpFormatter,
    )

    parser.add_argument(
        "-l",
        "--list",
        dest="list",
        help="list the kernels installed. Accepts one of the config options `--user` `--path` `--prefix`",
        action="store_true",
    )
    parser.add_argument(
        "-n",
        "--name",
        dest="name",
        help="The kernel name.",
        default="async",
    )
    parser.add_argument(
        "-u",
        "--user",
        dest="user",
        help="Select the user directory.",
        action="store_true",
    )
    parser.add_argument(
        "-V",
        "--version",
        dest="version",
        help="Print version.",
        action="store_true",
    )
    parser.add_argument(
        "--help-all",
        dest="help_all",
        help="Print help all.",
        action="store_true",
    )
    parser.add_argument(
        "--show-config",
        dest="show_config",
        help="Prints configuration.",
        action="store_true",
    )
    parser.add_argument(
        "--show-config-json",
        dest="show_config_json",
        help="Print configuration in json format.",
        action="store_true",
    )

    args, unknownargs = parser.parse_known_args()

    # Check for the 'start' command
    if unknownargs and unknownargs[0] in [Mode.start, Mode.install, Mode.uninstall]:
        mode = Mode(unknownargs.pop(0))
    else:
        mode = Mode.help
        for mode_ in Mode:
            if getattr(args, mode_, None):
                mode = mode_
                break

    flags, settings = to_flags_and_settings(unknownargs)

    match mode:
        case Mode.install:
            path = write_kernel_spec(user=args.user, name=args.name, flags=flags, **settings)
            print(f"Installed kernelspec {str(path)!r}")

        case Mode.uninstall:
            kernel_dir = get_kernel_dir(user=args.user, **settings)
            remove_kernelspec(kernel_dir, args.name)
            print(f"Uninstalled kernelspec {str(args.name)!r} from {str(kernel_dir)!r}")

        case Mode.list:
            kernel_dir = get_kernel_dir(user=args.user, **settings)
            kernels = get_kernel_info(kernel_dir)
            if not kernels:
                print(f"No kernels found in the folder {str(kernel_dir)!r}")
            else:
                width = max(map(len, kernels))
                m = len(kernels)
                header = f"Found {m} kernel{'s' if m > 1 else ''} found in the directory"
                n = max((len(str(kernel_dir)), len(header))) + 5
                print(f"{'─'}" * n)
                print(header)
                print(repr(str(kernel_dir)))
                # print("─" * n)
                print(f"{'Name'.ljust(width)}   Display name")
                print(f"{'─'}" * n)
                for name, info in kernels.items():
                    print(f"{name.ljust(width)}   {info.get('display_name')}")

        case Mode.version:
            print("async-kernel", async_kernel.__version__)
        case Mode.start | Mode.help_all | Mode.show_config | Mode.show_config_json:
            launcher: InterfaceStartType = import_launcher(settings.get("launcher", ""))
            settings["flags"] = flags
            try:
                launcher(settings)
            except KeyboardInterrupt:
                sys.exit(0)
        case _:
            parser.print_help()
    sys.exit(0)