Trait DataMap 

pub trait DataMap {
    type Entry: DataMapEntry;
    type Value;

    // Required methods
    fn id(&self) -> &str;
    fn decode(&self, value: &Tag) -> Option<Self::Value>;

    // Provided method
    fn ty(&self) -> DataMapType { ... }
}

A data map a mod registers and reads, typed (NeoForge’s DataMapType<R, T>): its id, the registry its entries are in (through DataMap::Entry), and how a value decodes.

Register it in data_map_types with DataMap::ty, then read an entry’s value with ItemKey::data or BlockKey::data. A value arrives as the NBT form of the JSON a file held: a whole number is an Int, or a Long past i32, a fraction a Double, a boolean a Byte, an object a Compound and an array a List. Integers outside signed 64-bit range and null at any nesting depth return DataMapError::Undecodable rather than changing the value. Fractional/exponent JSON tokens use the parser’s f64 value; empty and heterogeneous arrays retain their elements.

use mod_api::{DataMap, ItemKey, Tag};
/// `projecte:emc`: an item's EMC value.
struct Emc;
impl DataMap for Emc {
    type Entry = ItemKey;
    type Value = i64;
    fn id(&self) -> &str {
        "projecte:emc"
    }
    fn decode(&self, value: &Tag) -> Option<i64> {
        match value {
            Tag::Int(value) => Some(i64::from(*value)),
            Tag::Long(value) => Some(*value),
            _ => None,
        }
    }
}
assert_eq!(Emc.ty().registry, "minecraft:item");

Required Associated Types

type Entry: DataMapEntry

The registry entries the map attaches values to: ItemKey or BlockKey.

type Value

The value an entry holds.

Required Methods

fn id(&self) -> &str

The map’s id, mod_id:name, not in the minecraft namespace, as registered.

fn decode(&self, value: &Tag) -> Option<Self::Value>

Decode an entry’s value, refusing one of another shape.

Provided Methods

fn ty(&self) -> DataMapType

The type to push in data_map_types: this map’s id, for its entries’ registry.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors