from foo import bar
from foo import baz

from foo.bar import (func1, func2,)

__all__ = ['bar', 'baz', 'func1', 'func2']

def lazy_install(module_name, submodules, submod_attrs):
    import sys
    import importlib
    import importlib.util
    all_funcs = []
    for mod, funcs in submod_attrs.items():
        all_funcs.extend(funcs)
    name_to_submod = {
        func: mod for mod, funcs in submod_attrs.items()
        for func in funcs
    }

    def require(fullname):
        if fullname in sys.modules:
            return sys.modules[fullname]

        spec = importlib.util.find_spec(fullname)
        try:
            module = importlib.util.module_from_spec(spec)
        except:
            raise ImportError(f'Could not lazy import module {fullname}') from None
        loader = importlib.util.LazyLoader(spec.loader)

        sys.modules[fullname] = module

        # Make module with proper locking and get it inserted into sys.modules.
        loader.exec_module(module)

        return module

    def __getattr__(name):
        if name in submodules:
            fullname = f'{module_name}.{name}'
            attr = require(fullname)
        elif name name_to_submod:
            modname = name_to_submod[name]
            attr = importlib.import_module(
                f'{module_name}.{modname}'
            )
        else:
            raise AttributeError(f'No {module_name} attribute {name}')
        # Set module-level attribute so getattr is not called again
        globals()[name] = attr
        return attr
    return __getattr__

__getattr__ = lazy_install(
    __name__,
    submodules={
        'bar',
        'baz',
    },
    submod_attrs={
        'bar': [
            'func1',
            'func2',
        ],
    },
)

def __dir__():
    return __all__

__all__ = ['bar', 'baz', 'func1', 'func2']

from importlib import lazy_install

__getattr__ = lazy_install(
    __name__,
    submodules={'bar', 'baz'},
    submod_attrs={
        'bar': ['func1', 'func2',],
    },
)