About Bakery and Cakes

Note

If you want to run examples directly from the console, you may want to use ipython here.

$ pip install ipython

There are some thing you should know about bakery and cakes.

• Any class inherited from Bakery is becoming bakery ;)

Bakery is monostate

Though such a class is not singleton, but its instances share the same state. It is the Borg/Monostate (anti)pattern just because in Python class variables are shared by all instances.

from bakery import Bakery, Cake


class MyBakery(Bakery):
    my_list: list[int] = Cake([1, 2, 3])


async with MyBakery():
    bakery1: MyBakery = MyBakery()
    bakery2: MyBakery = MyBakery()
    assert bakery1 is not bakery2
    assert bakery1.my_list == bakery2.my_list == MyBakery.my_list()

Cakes are singletons

All cakes within bakery are singletons. Cakes are baked once on bakery open and unbaked once on bakery close. But you can easily copy cake once bakery is opened.

Info

After cake is copied you could do anything with it. Just remember, that after cake copy you'll receive a raw cake (pastry). And you need to bake it. See example below.

Warning

Note, that copy is an experimental feature yet. Cake copy is a shallow cake copy (it's going to be changed). Use it with care.

from copy import copy
from dataclasses import dataclass
from bakery import Bakery, Cake, Pastry, bake, unbake


@dataclass
class JsonKeeper:
    json: dict


class MyBakery(Bakery):
    json_keeper: JsonKeeper = Cake(JsonKeeper, json={"value": 42})


async with MyBakery() as bakery:
    keeper_copy: Pastry = copy(MyBakery.json_keeper)  # <<< Note: it's pastry, not cake ;)
    async with keeper_copy:  # <<< bake pastry
        assert keeper_copy().json == bakery.json_keeper.json

    await bake(keeper_copy)  # <<< bake pastry manually
    assert keeper_copy().json == bakery.json_keeper.json
    await unbake(keeper_copy)  # <<< unbake pastry

    keeper_copy()  # <<< raises ValueError. Pastry's not baked

Round brackets anywhere

No matter where you will decide to put parentheses while getting cake/attribute value, the result whould be the same in the end.

from dataclasses import dataclass
from typing import Optional
from bakery import Bakery, Cake


@dataclass
class NestedSettings:
    settings: Optional["NestedSettings"]
    json: dict


class MyBakery(Bakery):
    settings1: NestedSettings = Cake(NestedSettings, settings=None, json={"value": 42})
    settings2: NestedSettings = Cake(NestedSettings, settings=settings1, json={})


async with MyBakery() as bakery:
    assert (
        MyBakery.settings2.settings.json["value"]()
        == MyBakery.settings2.settings.json()["value"]
        == MyBakery.settings2.settings().json["value"]
        == MyBakery.settings2().settings.json["value"]
        == MyBakery().settings2.settings.json["value"]
        == bakery.settings2.settings.json["value"]
        == 42
    )