Data Class with Mutable Defaults

Step 1: Importing Dependencies

First, import the necessary modules and functions:

from dataclasses import dataclass, field

Step 2: Creating a Data Class

Now, let's create a data class named Fruit with mutable defaults:

@dataclass
class Fruit:
    name: str
    grams: float
    price_per_kilo: float
    edible: bool = True
    related_fruits: list = field(default_factory=list)

In this example, the Fruit class has fields for name, grams, price_per_kilo, edible (with a default value of True), and related_fruits (using field with default_factory to create an empty list).

Step 3: Creating Instances

Now, let's create instances of the Fruit class:

if __name__ == "__main__":
    # Creating an apple without specifying default values
    apple = Fruit(name="Apple", grams=100, price_per_kilo=5)

    # Creating a pear with custom values
    pear = Fruit(name="Pear", grams=250, price_per_kilo=10, edible=True, related_fruits=["Apple", "Orange"])

    # Printing the fruits
    print(apple)
    print(pear)
    print("Related Fruits:", pear.related_fruits)

In this example, the Fruit instances are created with and without specifying custom values. Note that default values are used for unspecified fields.

Now you can run your Python script, and you should see the output displaying the created Fruit instances.