Improving conciseness of ipaddress factory functions.

ipaddress 実装内の ip_address、ip_network、ip_interface、_prefix_from_ip_string のエントリーポイントを特定し、それらの周辺にある例外処理を確認します。提案されているループと抑制の変更を、既存のエラーパスを含む現在の動作と比較し、関連する ipaddress テストが引き続きパスすることを確認します。

Suggestion to refactor the 3 factory functions ip_address, ip_network, ip_interface.
In addition making a similar modification in the _prefix_from_ip_string function.

Currently the functions contain code which can be improved in terms of conciseness and extendability.

• try/catch containing a pass statement can be substituted with contextlib.suppress making the code more concise
• we can use a for loop which will iterate over the class objects to further increase conciseness

Current factory function implementations (docstrings not included for brevity)

def ip_address(address):
    try:
        return IPv4Address(address)
    except (AddressValueError, NetmaskValueError):
        pass

    try:
        return IPv6Address(address)
    except (AddressValueError, NetmaskValueError):
        pass

    raise ValueError(f'{address!r} does not appear to be an IPv4 or IPv6 address')


def ip_network(address, strict=True):
    try:
        return IPv4Network(address, strict)
    except (AddressValueError, NetmaskValueError):
        pass

    try:
        return IPv6Network(address, strict)
    except (AddressValueError, NetmaskValueError):
        pass

    raise ValueError(f'{address!r} does not appear to be an IPv4 or IPv6 network')


def ip_interface(address):
    try:
        return IPv4Interface(address)
    except (AddressValueError, NetmaskValueError):
        pass

    try:
        return IPv6Interface(address)
    except (AddressValueError, NetmaskValueError):
        pass

    raise ValueError(f'{address!r} does not appear to be an IPv4 or IPv6 interface')

Proposed function implementations

def ip_address(address):
    for ip_class in [IPv4Address, IPv6Address]:
        with contextlib.suppress(AddressValueError, NetmaskValueError):
            return ip_class(address)

    raise ValueError(f'{address!r} does not appear to be an IPv4 or IPv6 address')


def ip_network(address, strict=True):
    for network_class in [IPv4Network, IPv6Network]:
        with contextlib.suppress(AddressValueError, NetmaskValueError):
            return network_class(address, strict)

    raise ValueError(f'{address!r} does not appear to be an IPv4 or IPv6 network')


def ip_interface(address):
    for ip_interface_class in [IPv4Interface, IPv6Interface]:
        with contextlib.suppress(AddressValueError, NetmaskValueError):
            return ip_interface_class(address)

    raise ValueError(f'{address!r} does not appear to be an IPv4 or IPv6 interface')

current _prefix_from_ip_string function (docstrings and comments not included for brevity)

    @classmethod
    def _prefix_from_ip_string(cls, ip_str):
        try:
            ip_int = cls._ip_int_from_string(ip_str)
        except AddressValueError:
            cls._report_invalid_netmask(ip_str)

        try:
            return cls._prefix_from_ip_int(ip_int)
        except ValueError:
            pass

        ip_int ^= cls._ALL_ONES
        try:
            return cls._prefix_from_ip_int(ip_int)
        except ValueError:
            cls._report_invalid_netmask(ip_str)

Suggested improvement

    @classmethod
    def _prefix_from_ip_string(cls, ip_str):
        try:
            ip_int = cls._ip_int_from_string(ip_str)
        except AddressValueError:
            cls._report_invalid_netmask(ip_str)

        with contextlib.suppress(ValueError):
            return cls._prefix_from_ip_int(ip_int)

        ip_int ^= cls._ALL_ONES
        try:
            return cls._prefix_from_ip_int(ip_int)
        except ValueError:
            cls._report_invalid_netmask(ip_str)