Modularization in Smart Contract Development

Overview

Smart contract modules play a crucial role in structuring contracts into more manageable segments. Their reusability and ability to minimize code repetition make them valuable in contract development.

Module Creation

You can define modules either within the same crate as the primary contract or in a distinct standalone crate. The latter approach is beneficial for modules intended for use in various contracts.

A module is essentially a trait annotated with the #[klever_sc::module] macro, allowing standard smart contract functionalities such as endpoints, events, and storage mappers.

Consider the example of a storage module:

#[klever_sc::module]
pub trait StorageModule {
    #[view(getQuorum)]
    #[storage_mapper("firstStorage")]
    fn first_storage(&self) -> SingleValueMapper<usize>;

    #[view]
    #[storage_mapper("secondStorage")]
    fn second_storage(&self) -> SingleValueMapper<u64>;
}

In your core file, typically lib.rs, you should declare the module. For instance, if the storage module's file is storage.rs, it's declared as follows:

pub mod storage;

Integrating a Module

Modules can be included in other modules and contracts alike:

pub trait SetupModule:
    crate::storage::StorageModule
    + crate::util::UtilModule {

}

#[klever_sc::contract]
pub trait MainContract:
    setup::SetupModule
    + storage::StorageModule
    + util::UtilModule {

}

It's important to note that the main contract must implement all the modules used by any sub-modules. In the given example, the MainContract must implement UtilModule to use SetupModule, even if it doesn't directly use UtilModule.

Wrapping Up

Our modular system is designed to streamline the process of writing maintainable and reusable smart contract code.

For more examples and modules, visit: Klever VM SDK RS Modules