create_a_simple_python_object.md

TIL python: create a simple object from SimpleNamespace

I have a test which uses monkeypatching to replace an external service with mocked behaviour. It returns an object, but I want to just drop-in a simple object instead of instantiating the real class.

My TIl is the SimpleNamespace object.

Duck typing

...to the rescue. And thus types.SimpleNamespace.

from types import SimpleNamespace

# Create a SimpleNamespace object by passing attributes as keyword arguments
user_config = SimpleNamespace(username='Alice', theme='dark', notifications=True)

While we're on this topic, lets look at some alternatives:

Objects

Another way is to use the base object class:

class EmptyObject:
    pass

# Create two instances of the empty class
obj1 = EmptyObject()
obj1.username = 'Bob'
obj1.theme = 'light'
obj1.notifications = False

And then there's the 'namedtuple'

from collections import namedtuple

# Define two different named tuple types with the same fields
User = namedtuple('User', ['username', 'theme', 'notifications'])

p1 = User(username='Carol', theme='default',notifications=False)

All of these are similar in terms of accessing properties via dot notation; they each support some 'magic'/ standard methods - eg: len(), str(), repr() etc. But they're not supporting any other behaviour: They're just plain data-holding objects, useful in situations such as mocking in testing.