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OOP & classes

Classes, instances, methods, dataclasses, and object-oriented design in Python.

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How to Create an Immutable Money Class in Python with dataclasses

Define a frozen dataclass Money that holds an amount and currency, enforces non-negative amounts, and supports safe addition across matching currencies.

dataclass immutable money
Python 
from dataclasses import dataclass


@dataclass(frozen=True)
class Money:
    amount: float
    currency: str = "USD"

    def __post_init__(self) -> None:
        if self.amount < 0:
            raise ValueError("amount must be non-negative")

    def add(self, other: "Money") -> "Money":
        if self.currency != o…
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