Utilities¶

chanfig.utils.Singleton ¶

Bases: type

Metaclass for Singleton Classes.

Source code in chanfig/utils.py

Python
class Singleton(type):
    r"""
    Metaclass for Singleton Classes.
    """

    __instances__: Mapping[type, object] = {}

    def __call__(cls, *args: Any, **kwargs: Any):
        if cls not in cls.__instances__:
            cls.__instances__[cls] = super().__call__(*args, **kwargs)  # type: ignore[index]
        return cls.__instances__[cls]

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chanfig.utils.Null¶

Null is an instance of NULL.

Since the metaclass of NULL is Singleton, it is advised to use obj is Null to determine if obj is Null.

chanfig.utils.NULL ¶

NULL class.

get method in CHANfiG may accept None or Ellipse(...) as value of default. Therefore, it is mandatory to have a different default value for default.

Null is an instance of NULL and is recommended to be used as obj is Null.

Source code in chanfig/utils.py

Python
class NULL(metaclass=Singleton):
    r"""
    NULL class.

    `get` method in CHANfiG may accept `None` or `Ellipse`(`...`) as value of `default`.
    Therefore, it is mandatory to have a different default value for `default`.

    `Null` is an instance of `NULL` and is recommended to be used as `obj is Null`.
    """

    def __repr__(self):
        return "Null"

    def __nonzero__(self):
        return False

    def __len__(self):
        return 0

    def __call__(self, *args: Any, **kwargs: Any):
        return self

    def __contains__(self, name):
        return False

    def __iter__(self):
        return self

    def __next__(self):
        raise StopIteration

    def __getattr__(self, name):
        return self

    def __getitem__(self, index):
        return self

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chanfig.utils.JsonEncoder ¶

Bases: JSONEncoder

JSON encoder for Config.

Source code in chanfig/utils.py

Python
class JsonEncoder(JSONEncoder):
    r"""
    JSON encoder for Config.
    """

    def default(self, o: Any) -> Any:
        if hasattr(o, "__json__"):
            return o.__json__()
        return super().default(o)

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chanfig.utils.YamlDumper ¶

Bases: SafeDumper

YAML Dumper for Config.

Source code in chanfig/utils.py

Python
class YamlDumper(SafeDumper):  # pylint: disable=R0903
    r"""
    YAML Dumper for Config.
    """

    def increase_indent(self, flow: bool = False, indentless: bool = False):  # pylint: disable=W0235
        return super().increase_indent(flow, indentless)

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chanfig.utils.YamlLoader ¶

Bases: SafeLoader

YAML Loader for Config.

Source code in chanfig/utils.py

Python
class YamlLoader(SafeLoader):  # pylint: disable=R0901,R0903
    r"""
    YAML Loader for Config.
    """

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