Dataclass

Tipe Data di Python

Jason Myers

Instructor

Mengapa menggunakan dataclass

Dukungan nilai default
Representasi objek kustom
Konversi mudah ke tuple atau dictionary
Properti kustom
Instance beku

Melihat dataclass pertama kita

from dataclasses import dataclass

@dataclass
class Cookie:
    name: str
    quantity: int = 0

chocolate_chip = Cookie("chocolate chip", 13)
print(chocolate_chip.name)
print(chocolate_chip.quantity)

chocolate chip
13

Konversi mudah ke tuple atau dictionary

from dataclasses import asdict, astuple

ginger_molasses = Cookie("ginger molasses", 8)
asdict(ginger_molasses)

{'name': 'ginger molasses', 'quantity': 8}

astuple(ginger_molasses)

('ginger molasses', 8)

Properti kustom

from decimal import Decimal


@dataclass
class Cookie:
    name: str
    cost: Decimal
    quantity: int

   @property
   def value_of_goods(self):
      return int(self.quantity) * self.cost

Menggunakan properti kustom

peanut = Cookie("peanut butter", Decimal("1.2"), 8)

peanut.value_of_goods

Decimal('9.6')

Instance beku

@dataclass(frozen=True)
class Cookie:
    name: str
    quantity: int = 0

c = Cookie("chocolate chip", 10)

c.quantity = 15

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 4, in __setattr__
dataclasses.FrozenInstanceError: cannot assign to field 'quantity'

Ayo berlatih!

Tipe Data di Python