Trait Mappable

pub trait Mappable {
    type Key: ?Sized + ToOwned;
    type OwnedKey: From<<Self::Key as ToOwned>::Owned> + Clone;
    type Value: ?Sized + ToOwned;
    type OwnedValue: From<<Self::Value as ToOwned>::Owned> + Clone;
}

Mappable type with Key and Value.

Example

use fuel_storage::Mappable;
pub struct Contract;

impl Mappable for Contract {
    /// The `[u8; 32]` is a primitive type, so we can't optimize it more.
    type Key = Self::OwnedKey;
    type OwnedKey = [u8; 32];
    /// It is optimized to use slice instead of vector.
    type Value = [u8];
    type OwnedValue = Vec<u8>;
}

Required Associated Types

type Key: ?Sized + ToOwned

The key type is used during interaction with the storage. In most cases, it is the same as Self::OwnedKey.

type OwnedKey: From<<Self::Key as ToOwned>::Owned> + Clone

The owned type of the Key retrieving from the storage.

type Value: ?Sized + ToOwned

The value type is used while setting the value to the storage. In most cases, it is the same as Self::OwnedValue, but it is without restriction and can be used for performance optimizations.

type OwnedValue: From<<Self::Value as ToOwned>::Owned> + Clone

The owned type of the Value retrieving from the storage.

Implementors