dataclass default attribute code example

Example 1: python data object

from dataclasses import dataclass

@dataclass
class InventoryItem:
    """Class for keeping track of an item in inventory."""
    name: str
    unit_price: float
    quantity_on_hand: int = 0

    def total_cost(self) -> float:
        return self.unit_price * self.quantity_on_hand

Example 2: dataclass python

def __init__(self, name: str, unit_price: float, quantity_on_hand: int=0):
    self.name = name
    self.unit_price = unit_price
    self.quantity_on_hand = quantity_on_hand
    
    def total_cost(self) -> float:
        return self.unit_price * self.quantity_on_hand

# Is the same as:
    
from dataclasses import dataclass

@dataclass
class InventoryItem:
    """Class for keeping track of an item in inventory."""
    name: str
    unit_price: float
    quantity_on_hand: int = 0
      
    def total_cost(self) -> float:
        return self.unit_price * self.quantity_on_hand