Repository: pypa/pip
File: src/pip/_internal/cli/cmdoptions.py (Python)

Code before:
    Process a value provided for the --no-use-pep517 option.

    This is an optparse.Option callback for the no_use_pep517 option.
    """
    # Since --no-use-pep517 doesn't accept arguments, the value argument
    # will be None if --no-use-pep517 is passed via the command-line.
    # However, the value can be non-None if the option is triggered e.g.
    # by an environment variable, for example "PIP_NO_USE_PEP517=true".
    if value is not None:
        msg = """A value was passed for --no-use-pep517,
        probably using either the PIP_NO_USE_PEP517 environment variable
        or the "no-use-pep517" config file option. Use an appropriate value
        of the PIP_USE_PEP517 environment variable or the "use-pep517"
        config file option instead.
        """
        raise_option_error(parser, option=option, msg=msg)

    # If user doesn't wish to use pep517, we check if setuptools and wheel are installed
    # and raise error if it is not.
    for package in ("setuptools", "wheel"):
        if not importlib.util.find_spec(package):
            msg = (
                f"It is not possible to use --no-use-pep517 "
                f"without {package} installed."
            )
            raise_option_error(parser, option=option, msg=msg)

    # Otherwise, --no-use-pep517 was passed via the command-line.
    parser.values.use_pep517 = False


use_pep517: Any = partial(
    Option,
    "--use-pep517",
    dest="use_pep517",
    action="store_true",
    default=None,
    help="Use PEP 517 for building source distributions "
    "(use --no-use-pep517 to force legacy behaviour).",
)

no_use_pep517: Any = partial(
    Option,
    "--no-use-pep517",
    dest="use_pep517",
    action="callback",
    callback=_handle_no_use_pep517,
    default=None,
    help=SUPPRESS_HELP,
)


Review comment (suggestion):
It’s annoying if you see an error about setuptools, install it, and only be greeted by another error telling you to install wheel. We should combine the two into one.

Code after:
    Process a value provided for the --no-use-pep517 option.

    This is an optparse.Option callback for the no_use_pep517 option.
    """
    # Since --no-use-pep517 doesn't accept arguments, the value argument
    # will be None if --no-use-pep517 is passed via the command-line.
    # However, the value can be non-None if the option is triggered e.g.
    # by an environment variable, for example "PIP_NO_USE_PEP517=true".
    if value is not None:
        msg = """A value was passed for --no-use-pep517,
        probably using either the PIP_NO_USE_PEP517 environment variable
        or the "no-use-pep517" config file option. Use an appropriate value
        of the PIP_USE_PEP517 environment variable or the "use-pep517"
        config file option instead.
        """
        raise_option_error(parser, option=option, msg=msg)

    # If user doesn't wish to use pep517, we check if setuptools and wheel are installed
    # and raise error if it is not.
    packages = ("setuptools", "wheel")
    if not all(importlib.util.find_spec(package) for package in packages):
        msg = (
            f"It is not possible to use --no-use-pep517 "
            f"without {' and '.join(packages)} installed."
        )
        raise_option_error(parser, option=option, msg=msg)

    # Otherwise, --no-use-pep517 was passed via the command-line.
    parser.values.use_pep517 = False


use_pep517: Any = partial(
    Option,
    "--use-pep517",
    dest="use_pep517",
    action="store_true",
    default=None,
    help="Use PEP 517 for building source distributions "
    "(use --no-use-pep517 to force legacy behaviour).",
)

no_use_pep517: Any = partial(
    Option,
    "--no-use-pep517",
    dest="use_pep517",
    action="callback",
    callback=_handle_no_use_pep517,
    default=None,
    help=SUPPRESS_HELP,
)