Demo of how to use contextlib (with dogs!)

context_example.py

"""
A fun demonstration of Python's contextlib module using a doghouse example.
This file shows both class-based and decorator-based approaches to context managers.
"""

import contextlib
from typing import List, Optional


class Dog:
    """A simple dog class that can bark and wag its tail."""

    def __init__(self, name: str):
        self.name = name
        print(f"{name} jumps into the doghouse! Woof!")

    def bark(self) -> None:
        """Make the dog bark."""
        print(f"{self.name}: Woof! Woof!")

    def wag_tail(self) -> None:
        """Make the dog wag its tail."""
        print(f"{self.name} wags tail happily!")


class Doghouse:
    """A context manager that represents a doghouse where dogs can be added and managed."""

    def __init__(self):
        self.dogs: List[Dog] = []
        print("Building a new doghouse...")

    def __enter__(self):
        """Method called when entering the context (with statement)."""
        print("Doghouse is ready for dogs!")
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        """Method called when exiting the context."""
        num_dogs = len(self.dogs)
        if num_dogs == 0:
            print("Closing the empty doghouse.")
        else:
            print(f"Closing the doghouse with {num_dogs} dog(s).")
            for dog in self.dogs:
                print(f"Goodbye, {dog.name}!")

    def add(self, name: str) -> Dog:
        """Add a new dog to the doghouse."""
        dog = Dog(name)
        self.dogs.append(dog)
        return dog

    def find(self, name: str) -> Optional[Dog]:
        """Find a dog by name."""
        for dog in self.dogs:
            if dog.name == name:
                return dog
        return None

    def all_bark(self) -> None:
        """Make all dogs bark."""
        print("All dogs are barking!")
        for dog in self.dogs:
            dog.bark()


# Alternative implementation using the @contextmanager decorator
@contextlib.contextmanager
def simple_doghouse():
    """A simpler doghouse implementation using the contextmanager decorator."""
    print("Building a new doghouse...")
    dogs = []

    class SimpleDoghouse:
        def add(self, name: str) -> Dog:
            dog = Dog(name)
            dogs.append(dog)
            return dog

        def all_bark(self) -> None:
            print("All dogs are barking!")
            for dog in dogs:
                dog.bark()

    try:
        print("Doghouse is ready for dogs!")
        yield SimpleDoghouse()
    finally:
        num_dogs = len(dogs)
        if num_dogs == 0:
            print("Closing the empty doghouse.")
        else:
            print(f"Closing the doghouse with {num_dogs} dog(s).")
            for dog in dogs:
                print(f"Goodbye, {dog.name}!")


# Helper function to make it easier to use
def doghouse():
    """Create a new doghouse context manager."""
    return Doghouse()


if __name__ == "__main__":
    # Using the class-based context manager
    with doghouse() as house:
        sparky = house.add(name="Sparky")
        sparky.bark()
        house.add(name="Rex")
        house.all_bark()

    print("\n--- Using the decorator-based approach ---\n")

    # Using the decorator-based context manager
    with simple_doghouse() as house:
        house.add(name="Bella")
        house.add(name="Max")
        house.all_bark()