ABC
- Python course
- Intermediate
- Lesson 47/116
- 5 min
Learn abstract classes with abc.ABC.
Abstract class (ABC)
An abstract class is a class that you do not instantiate directly and that acts as a template for subclasses. In Python you define it by inheriting from the ABC class in the abc module.
Example: from abc import ABC\nclass Animal(ABC):\n pass. Here Animal is now an abstract class. If you try to create an instance with Animal() you get a TypeError; but you can subclass it and instantiate the subclass. Abstract classes enforce a shared interface.
Inheriting from ABC
The shortest way to define an abstract class is to inherit from ABC. Even if you put no abstract methods in the body, ABC inheritance blocks any attempt to instantiate. This signals “this class should not be used alone”.
An abstract class gives subclasses a common behavior frame. A subclass inherits the abstract class and fills in the missing methods. So different subclasses conform to the same interface; the caller does not need to know which subclass it is.
Practice Define the abstract class
Start with from abc import ABC. Define an abstract class Animal(ABC); its body should be pass. Then print the abstract base relation with print(issubclass(Animal, ABC)).
Starter code
# Import ABC from abc and define the Animal abstract classSample solution
# Import ABC from abc and define the Animal abstract class
from abc import ABC
class Animal(ABC):
pass
print(issubclass(Animal, ABC))Expected output
True
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What happens after defining Animal(ABC)?
- Animal() returns a new instance
- Animal() raises TypeError Correct answer
- Animal automatically becomes a subclass
- Animal is ignored
Explanation: An abstract class cannot be instantiated directly; it raises TypeError.
2 Complete the import line
from ____ import ABC
class Animal(ABC):
passfrom abc import ABC
class Animal(ABC):
passExplanation: The abc module contains the ABC class.
3 Match the ABC parts
| Term | Meaning |
|---|---|
abc |
Module |
ABC |
Base class |
class Animal(ABC) |
Abstract definition |
TypeError |
Instantiation error |