Implementing items

[kipyin]

Here is a scratch of how implementing items using classes should look like:

@attr.s
class Item:
    """An Item in the Pokémon world."""

    cost: int = attr.ib(init=False)
    sell_price: int = attr.ib(init=False)
    pocket: str = attr.ib(init=False)

@attr.s(slots=True)
class _Medicine(Item):

    cost: int = attr.ib(init=False)
    sell_price: int = attr.ib(init=False)
    pocket: str = attr.ib(init=False)
    recover: int = attr.ib(init=False)

    def battle_effect(self, target):
        target.current_hp = min(target.permanent_stats.hp, self.recover)

    def field_effect(self, target):
        self.battle_effect(target)

@attr.s
class Potion(_Medicine):

    def __attrs_post_init__(self):
        self.cost = 300
        self.sell_price = self.cost // 2
        self.pocket = 'items'
        self.recover = 20

@attr.s
class SuperPotion(_Medicine):

    def __attrs_post_init__(self):
        self.cost = 700
        self.sell_price = self.cost // 2
        self.pocket = 'items'
        self.recover = 50

Now, we should be able to do the following:

>>> from pokemaster.pokemon import Pokemon
>>> from pokemaster.item import SuperPotion
>>> super_potion = SuperPotion()
>>> p = Pokemon(national_id=1, level=100)
>>> print(f'The original HP: {p.current_hp}')
The original HP: 216
>>> p.current_hp = 0
>>> print(f'The HP should be 0: {p.current_hp}')
The HP should be 0: 0
>>> super_potion.battle_effect(p)
>>> print(f'HP after recovered by {super_potion}: {p.current_hp}')
HP after recovered by SuperPotion(cost=700, sell_price=350, pocket='items', recover=50): 50

Is this a good enough solution to carry on?

[kipyin]

Use class variables instead:

@attr.s(slots=True, auto_attribs=True)
class Potion(_Medicine):
    COST: ClassVar[int] = 300
    SELL_PRICE: ClassVar[int] = 150
    RECOVER: ClassVar[int] = 20

    @classmethod
    def field_effect(cls, target):
        target.current_hp += min(cls.RECOVER, target.permanent_stats.hp - target.current_hp)

[kipyin]

float('inf')

For items like Full Restore or Max Potion, we can use float('inf') to represent the recover amount:

@attr.s
class MaxPotion(_Medicine):
    COST: ClassVar[int] = 2500
    SELL_PRICE: ClassVar[int] = 1250
    RECOVER: ClassVar[float] = float('inf')

This way we don't have to override the class methods _Medicine.field_effect().

Add a complementary database/data file to hold all the parameters?

Hand-writing all the class declarations is extremely repetitive (you have to write ClassVar[int] for all class variables). Although if those are class methods and we don't have any attributes, what stops us from doing COST = 200 instead? We don't have to set auto_attribs=True at all! This simplifies a class to:

@attr.s
class HyperPotion(_Medicine):
    COST = 1200
    SELL_PRICE = 600
    RECOVER = 200

(Maybe we can even drop @attr.s if we don't need comparison, hashing, slots, etc.?)

Instances of an Item class

If all methods and attributes are class-level, what is the difference between a Hyper Potion A and another Hyper Potion B? Apparently, hyper_potion_A is not hyper_potion_B, but should hyper_potion_A == hyper_potion_B?

If we want to use items as keys in dictionaries (e.g. to represent the content of a bag), items should be hashable. What is the meaning of {hyper_potion: 5}? Here hyper_potion is an item, and yet it is used to represent 5 different items. Oxymoron? In this case, here is an absolutely correct but totally unnecessary way to represent a bag: [HyperPotion() for _ in range(10)]. This would have 5 distinct Hyper Potions in the bag, meaningfully.

[kipyin]

This won't be included in release v0.1. Maybe v0.2. Maybe.

[kipyin]

Yes, the effect must be hard-coded. No, the data (recovery, cost, etc.) must not be hard-coded.

[kipyin]

All item has an effect column, which contains the descriptions on the item effect. Is it possible to use regex (or even NLP) to realize the effects?

[kipyin]

It works for medicines, since their descriptions are easy to understand. How about other items?

Take the item IronBall for example:

Held: Holder's Speed is halved. Negates all Ground-type immunities, and makes Flying-types take neutral damage from Ground-type moves. Arena Trap. Spikes, and Toxic Spikes affect the holder.

How do we even remotely regex/NLP this effect?