Unavailable Object

A placeholder object for optional dependencies.

Usage

from unavailable_object import UnavailableObject

try:
    import optional_module
except ImportError:
        optional_module = UnavailableObject("optional_module")

Type Checking

To not disturb the type checker, the alternative definition of optional_object should be guarded by if not TYPE_CHECKING and type annotations put in quotes:

from typing import TYPE_CHECKING
from unavailable_object import UnavailableObject

try:
    import optional_module
except ImportError:
    if not TYPE_CHECKING:
        optional_module = UnavailableObject("optional_module")

def foo(arg: "optional_module.SomeType") -> None:
    pass