What is the function form of star import in Python 3

Question

What is the equivalent of import * in Python using functions (presumably from importlib)?

I know that you can import a module with mod = __import__(...), which will delegate to whatever the currently configured implementation is. You can also do something like

mod_spec = importlib.utl.spec_from_file_location(...) mod = importlib.util.module_from_spec(mod_spec) mod_spec.loader.exec_module(mod) 

which allows you to do crazy things like injecting things into the module by inserting them before the call to exec_module. (Courtesy of https://stackoverflow.com/a/67692/2988730 and https://stackoverflow.com/a/38650878/2988730)

However, my question remains. How does import * work in function form? What function determines which names to load from a module depending on the presence/contents of __all__?

Answer 1

There's no function for from whatever import *. In fact, there's no function for import whatever, either! When you do

mod = __import__(...) 

the __import__ function is only responsible for part of the job. It provides you with a module object, but you have to assign that module object to a variable separately. There's no function that will import a module and assign it to a variable the way import whatever does.

---

In from whatever import *, there are two parts:

• prepare the module object for whatever
• assign variables

The "prepare the module object" part is almost identical to in import whatever, and it can be handled by the same function, __import__. There's a minor difference in that import * will load any not-yet-loaded submodules in a package's __all__ list; __import__ will handle this for you if you provide fromlist=['*']:

module = __import__('whatever', fromlist=['*']) 

The part about assigning names is where the big differences occur, and again, you have to handle that yourself. It's fairly straightforward, as long as you're at global scope:

if hasattr(module, '__all__'):     all_names = module.__all__ else:     all_names = [name for name in dir(module) if not name.startswith('_')]  globals().update({name: getattr(module, name) for name in all_names}) 

Function scopes don't support assigning variables determined at runtime.