What use is there for defining magic methods outside of a class?

Question

What happens if I define a magic method outside a class?
For example, say I do:

def __str__(stuff):
    return "chicken"

directly inside the module.

When would something like this be useful? I thought it might be useful if I import this module named module1 elsewhere and try to do print(module1), but that just prints out the file location and other stuff.

So is there even any use for using a magic method outside a class? Is it even really a magic method any more?

Answer 1

At the moment (Python 3.9), two module-level magic methods can be defined: __getattr__ and __dir__ (see PEP 562 for details).

• __getattr__ overrides attribute access on that module, including imports of the form from x import y.
• __dir__ overrides what is returned by dir(module).

For example:

# foo.py

def __getattr__(name):
    return name

def __dir__():
    return ['foo', 'bar']

Then we can use it in the following way:

>>> import foo
>>> dir(foo)
['bar', 'foo']
>>> from foo import bar
>>> bar
'bar'