CompclassMeta (metaclass)

CompclassMeta

Bases: ABCMeta

Metaclass that adds class attributes/methods from delegates to clsname object as class properties.

Usage:

class Foo:
    a = 1

    def __len__(self) -> int:
        # custom len method
        return 42

class Bar(metacls=CompclassMeta, delegates={"_foo": ("a", "__len__")}):
    def __init__(self, foo: Foo):
        self._foo = foo

foo = Foo()
bar = Bar(foo)

bar.a  # -> 1 (instead of bar._foo.a)
len(bar)  # -> 42 (instead of len(bar._foo))

Source code in compclasses/_meta.py

class CompclassMeta(ABCMeta):
    """Metaclass that adds class attributes/methods from `delegates` to `clsname` object as class properties.

    Usage:

    ```python
    class Foo:
        a = 1

        def __len__(self) -> int:
            # custom len method
            return 42

    class Bar(metacls=CompclassMeta, delegates={"_foo": ("a", "__len__")}):
        def __init__(self, foo: Foo):
            self._foo = foo

    foo = Foo()
    bar = Bar(foo)

    bar.a  # -> 1 (instead of bar._foo.a)
    len(bar)  # -> 42 (instead of len(bar._foo))
    ```
    """

    def __new__(
        cls: Type,
        clsname: str,
        bases: Tuple[Type, ...],
        attrs: Dict[str, Any],
        delegates: Dict[str, Union[Iterable[str], delegatee]],
        verbose: bool = True,
        log_func: Callable[[str], None] = logger.info,
    ) -> CompclassMeta:
        """
        Arguments:
            cls: Metaclass
            clsname: Class name
            bases: Base classes
            attrs: Class attributes
            delegates: Key-value pair of delegates.

                - key: Name of the class/instance attribute to which the delegate instance is assigned to.
                - value: Must be either a sequence/iterable of method names or a `delegatee` instance.
                    They represent the attributes/methods to forward.

            verbose: Defines the level of verbosity when setting those forwarded methods.
            log_func: Function to use for logging, if verbose is set to True.
        """

        for _name, _to_inject in generate_properties(delegates, verbose, log_func):
            attrs[_name] = _to_inject

        return super().__new__(cls, clsname, bases, attrs)

__new__(clsname, bases, attrs, delegates, verbose=True, log_func=logger.info)

Parameters:

Name	Type	Description	Default
cls	Type	Metaclass	required
clsname	str	Class name	required
bases	Tuple[Type, ...]	Base classes	required
attrs	Dict[str, Any]	Class attributes	required
delegates	Dict[str, Union[Iterable[str], delegatee]]	Key-value pair of delegates. key: Name of the class/instance attribute to which the delegate instance is assigned to. value: Must be either a sequence/iterable of method names or a delegatee instance. They represent the attributes/methods to forward.	required
verbose	bool	Defines the level of verbosity when setting those forwarded methods.	True
log_func	Callable[[str], None]	Function to use for logging, if verbose is set to True.	logger.info

Source code in compclasses/_meta.py

def __new__(
    cls: Type,
    clsname: str,
    bases: Tuple[Type, ...],
    attrs: Dict[str, Any],
    delegates: Dict[str, Union[Iterable[str], delegatee]],
    verbose: bool = True,
    log_func: Callable[[str], None] = logger.info,
) -> CompclassMeta:
    """
    Arguments:
        cls: Metaclass
        clsname: Class name
        bases: Base classes
        attrs: Class attributes
        delegates: Key-value pair of delegates.

            - key: Name of the class/instance attribute to which the delegate instance is assigned to.
            - value: Must be either a sequence/iterable of method names or a `delegatee` instance.
                They represent the attributes/methods to forward.

        verbose: Defines the level of verbosity when setting those forwarded methods.
        log_func: Function to use for logging, if verbose is set to True.
    """

    for _name, _to_inject in generate_properties(delegates, verbose, log_func):
        attrs[_name] = _to_inject

    return super().__new__(cls, clsname, bases, attrs)