dddentity

DDD entity.

Usage

from dddentity import Entity, ref

UserId = str


class User(Entity[UserId]):
    def __init__(self, id: UserId, name: str) -> None:
        self.id = id
        self.name = name

    def _ref_(self) -> UserId:
        return self.id


assert User("0001", "Gilgamesh") == User("0001", "Bilgamesh")

assert ref(User("0002", "Enkidu")) == "0002"

Caveat

Currently eq=False must be set when using with dataclasses to prevent to generate __eq__() method by dataclass.

@dataclass(eq=False)
class User(Entity[UserId]):
    ...

API

Module dddentity

abstract class Entity[T]

Entity class. Classes implementing this class must implement abstract method _ref_().

This class is hashable, satisfying the following conditions:

• entity1 == entity2 iff entity1._ref_() == entity2._ref_()
• hash(entity) == hash(entity._ref_())

where entity, entity1, entity2 are entities.

type parameter T

Type of the identifier of the entity, which must be hashable.

abstract method _ref_() -> T

Shall return the identifier of the entity.

function ref(entity: Entity[T]) -> T

Return entity._ref_().