A constructor for dataclasses with randomized attribute values

Question

Hi could someone explain whats happening here:
i want to instantiate objects with random values.

@dataclass
class Particle:
    pos = (random.randint(0, 800), random.randint(0, 800))

for _ in range(3):
    p = Particle()
    print(p.pos)

prints:

expected behaviour wold be three tuples with different values. Whats happening here??

(when i use a normal class it works as expected)

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Answer 1

You are creating the random integers only once at class definition. What you want is a default factory for your value.

Example:

def rndints():
    return (random.randint(0, 800), random.randint(0, 800))

@dataclass
class Particle:
    pos = field(default_factory=rndints)

Answered By: Carlos Horn

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