A decorator for delaying the import of a module in Python.

example.py

from imports import imports

@imports("torch.cuda")
def is_cuda_available():
    return torch.cuda.is_available()

imports.py

import functools
import importlib 
from typing import Optional
from types import ModuleType


class imports:
    """A decorator for functions that require optional dependencies.
    """

    module: typing.Optional["ModuleType"]

    def __init__(self, module_name: str) -> None:
        self.module_name = module_name
        self.module = None

    def __call__(self, func: "_F") -> "_F":

        @functools.wraps(func)
        def newfunc(*args, **kwargs):
            if self.module is None:
                self.module = importlib.import_module(self.module_name)
            basename = self.module_name.split(".")[-1]
            func.__globals__[basename] = self.module
            return func(*args, **kwargs)

        return newfunc # type: ignore