construct `__all__` automatically in Python

exporter.py

from typing import Collection, List, Dict


class Export:
    """
    construct __all__ using decorator

    Example:
    >>> import os, sys
    >>> from exporter import Export
    >>>
    >>> export = Export()
    >>> __all__ = export.__all__
    >>>
    >>> # all classes or funcions marked with @export are exported.
    >>> @export
    >>> def foo_method():
    >>>     pass
    >>>
    >>> class FooClass:
    >>>     pass
    >>>
    >>> def bar_method():
    >>>     pass
    >>>
    >>> @export
    >>> class BarClass:
    >>>     pass
    >>>
    >>> # __all__ == ['foo_method', 'BarClass']
    
    """

    def __init__(self, all: Collection[str] = None):
        self._default_all = all or tuple()
        self._all = list(self._default_all)

    def export(self, o):

        if isinstance(o, str):
            self._all.append(o)
        elif hasattr(o, '__name__'):
            self._all.append(o.__name__)

        return o

    def __call__(self, *args, **kwargs):
        return self.export(*args)

    def build_all(self) -> List[str]:
        return self._all

    @property
    def __all__(self):
        return self.build_all()


class ExportBelow:
    """
    construct __all__ using locals()

    Example:
    >>> import os, sys
    >>> from exporter import ExportBelow
    >>>
    >>> def foo_method():
    >>>     pass
    >>>
    >>> class FooClass:
    >>>     pass
    >>>
    >>> __all__ = ExportBelow(locals())
    >>> # all module level variables below are exported.
    >>>
    >>> def bar_method():
    >>>     pass
    >>>
    >>> class BarClass:
    >>>     pass
    >>>
    >>> # __all__ == ['bar_method', 'BarClass']
    
    """

    def __init__(self, locals_dic: Dict):
        self._locals_dic = locals_dic
        self._begin_locals_dic = dict(locals_dic)
        self._all_list = None
        self._excludes = ['__all__']

    @property
    def _all(self):
        if self._all_list is None:
            self._all_list = list(set(self._locals_dic.keys()) - set(self._begin_locals_dic.keys()) - set(self._excludes))
            self._locals_dic = None  # release reference to locals
            self._begin_locals_dic = None
        return self._all_list

    def __getitem__(self, item):
        return self._all.__getitem__(item)