Inventory limits

Unstable: everything in this chapter needs the unstable feature and may change in any release (Stability).

A mod changes how many of an item one slot holds and how many slots a chest has with the same changes data packs make, merged by the same rule with every pack and mod. A change declared with Load::declare_change takes its value any time after init, such as from a setting that differs per world.

Declare at init, set later

use enshwick::content::categories::ItemCategoryMask;
use enshwick::content::changes::{ChangeHandle, Field, Items, Target, Value};

fn init(load: &mut enshwick::Load<'_>) -> Result<(ChangeHandle, ChangeHandle), enshwick::Off> {
    let materials = Target::Items(Items::Category(ItemCategoryMask::MATERIALS));
    let stacks = load.declare_change(materials, Field::MaxStackSize, "stacks")?;
    let chests = load.declare_change(Target::Items(Items::Containers), Field::Slots, "chests")?;
    stacks.set(Value::Times(4.0)).map_err(|why| enshwick::Off::new(why.to_string()))?;
    chests.set(Value::Set(48.0)).map_err(|why| enshwick::Off::new(why.to_string()))?;
    Ok((stacks, chests))
}

• Target::Entry names one vanilla item; Target::Items picks every item of some categories, every item that stacks, or every item that places a container, read from the game’s data.
• Until set, the change leaves every value as the other mods make it. reset takes the mod’s value out again.
• Each set merges every change again and builds the items, chest templates, recipes and loot tables it reaches anew in place. It allocates: call it when a setting changes, not every frame.
• Values take the same ranges as data packs: a stack size from 1 to 65535, slots from 8 to 128 in steps of 8.

Which games read it

The server decides. Its game cuts every stack above an item’s stack size and sizes every chest it places. A player’s game uses its own stack sizes for the split and merge it offers and for what it shows, so every side needs the same value. A change of an item or a recipe therefore needs a mod with join: true, which sets the value from a synced setting (#[config(startup, sync)], see join values): a player joining a server takes the server’s value. Loot changes reach the server alone and need no join.

Chests

A chest keeps the size it was placed with, which the save holds. A new size reaches chests placed after the change; a chest a player upgrades takes the new size of the chest it becomes. Slots only grow: a chest a player upgrades moves every item it holds.

Stack sizes and saved worlds

The game cuts saved stacks above an item’s stack size when a world loads, before any per-world setting applies. So the loader keeps every stack size above the game’s that was in force when a world was saved, in mod-data/enshwick/kept-stacks.toml, and serves at least that size from the start, for every mod and pack and without them:

info  stacks of 3f4093ae-75ed-4e5d-bd0b-784ba83b88f5 stay at 999, not 100: a saved world may hold stacks that large

• A lower value from a mod or pack takes effect only above the kept size. To lower it, split every larger stack, then delete the item’s line in the file while the game is stopped.
• Removing the mod that raised a size keeps the size too: the loader still serves it.
• While any size is kept, the loader holds the game: on a game build it does not know, which it would leave vanilla, the game stops before a world loads and cuts nothing.