Adding custom attributes in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a custom attribute in Python?

A custom attribute is a user-defined variable attached to an object or class to store extra information beyond built-in attributes.

beginner

How do you add a custom attribute to an existing object in Python?

You assign a value to a new attribute name using dot notation, like object.new_attribute = value.

intermediate

Can you add custom attributes to built-in types like int or str?

No, built-in types like int or str do not allow adding custom attributes directly because they are immutable and don't have a writable __dict__.

intermediate

What is the difference between adding custom attributes to an instance vs. a class?

Adding to an instance affects only that object, while adding to a class affects all instances of that class unless overridden.

beginner

Show a simple example of adding a custom attribute to a class instance.

Example:<br><pre>class Dog:
    pass

my_dog = Dog()
my_dog.age = 5  # custom attribute
print(my_dog.age)  # Output: 5</pre>

How do you add a custom attribute named 'color' with value 'red' to an object 'car'?

A car['color'] = 'red'

B car.color = 'red'

C car.add_attribute('color', 'red')

D setattr(car, 'color')

You use dot notation to add a custom attribute: car.color = 'red'.

Which of these can you NOT add custom attributes to directly?

A User-defined class instances

B Objects created from classes

C Custom classes

D Built-in types like int

Built-in types like int do not allow adding custom attributes directly.

What happens if you add a custom attribute to a class?

A All instances of the class get the attribute unless overridden

B The attribute is deleted from instances

C Only that class instance gets the attribute

D It raises an error

Adding an attribute to a class makes it available to all instances unless they have their own attribute with the same name.

Which function can also add attributes dynamically to an object?

A delattr()

B getattr()

C setattr()

D hasattr()

setattr(object, name, value) adds or changes an attribute dynamically.

If you add an attribute to an instance, can it override a class attribute with the same name?

A Yes, instance attribute overrides class attribute

B No, class attribute always takes precedence

C Only if you delete the class attribute first

D It causes an error

Instance attributes override class attributes with the same name.

Explain how to add a custom attribute to a Python object and what happens when you add it to a class instead.

Think about the difference between instance and class level.

Describe why you cannot add custom attributes to built-in types like int or str in Python.

Consider how built-in types are implemented.