Transition Away from Currency Trait

Severity: Medium

Description

The Currency trait in Substrate is deprecated and should no longer be used in new implementations. Continuing to rely on deprecated traits risks compatibility issues with future framework updates and limits access to newer, more flexible features. Transitioning to the recommended traits, such as those in the fungible module (Inspect, Mutate, ...), ensures forward compatibility, aligns with modern development practices, and leverages the latest improvements in the Substrate ecosystem.

What should be avoided

Avoid using the deprecated Currency trait in new implementations:

#![allow(unused)]
fn main() {
use frame_support::traits::Currency;

#[pallet::config]
pub trait Config: frame_system::Config {
    // Currency trait is deprecated
    type Currency: Currency<Self::AccountId>;
}
}

In this example:

• The Currency trait is used to handle account balances. This trait is already deprecated and should not be used.

Best practice

The usage of fungible traits is preferred instead.

#![allow(unused)]
fn main() {
// Import the traits from the fungible module
use frame_support::traits::fungible::{Inspect, Mutate};

#[pallet::config]
pub trait Config: frame_system::Config {
    // Use the preferred traits
	type Currency: Inspect<Self::AccountId> + Mutate<Self::AccountId>;
}
}