ABCs
Abstract base classes define interfaces. Subclasses must implement all abstract methods or instantiation raises TypeError.
Python
Intermediate
4 min read
Abstract Base Classes
Example
from abc import ABC, abstractmethod
class Notifier(ABC):
@abstractmethod
def send(self, message: str, recipient: str) -> bool: ...
@abstractmethod
def validate_recipient(self, recipient: str) -> bool: ...
def notify(self, message, recipient): # concrete method
if self.validate_recipient(recipient):
return self.send(message, recipient)
raise ValueError("Invalid recipient")
class EmailNotifier(Notifier):
def send(self, message, recipient): return smtp_send(recipient, message)
def validate_recipient(self, r): return "@" in r Pro Tip
ABCs document contracts explicitly — subclasses get a TypeError at instantiation, not at runtime call.