A Software Development Kit (SDK) and build tool for writing smart contracts in Rust on Wasm blockchains.
Currently, the focus is on the Soroban VM, but the same ideas apply to other VMs.
To install just
, run the following command:
cargo install just
To set up the environment, run:
just setup
To see redeployment in action, use:
just redeploy
A subcontract peice of a contract which is responsible for a subset of the contracts API.
Here's an example of how to create a subcontract:
#[contracttype]
#[derive(IntoKey)]
pub struct Messages(Map<Address, String>);
This generates the following implementation:
impl IntoKey for Messages {
type Key = IntoVal<Env, RawVal>;
fn into_key() -> Self::Key {
String::from_slice("messages")
}
You can also create and implement external APIs for subcontracts:
#[subcontract]
pub trait IsPostable {
fn messages_get(&self, author: Address) -> Option<String>;
fn messages_set(&mut self, author: Address, text: String);
}
The Core
trait provides the minimum logic needed for a contract to be redeployable. A contract should be able to be redeployed to another wasm binary that can also be redeployed. Redeployment requires the contract to have an admin, as it would be undesirable for any account to redeploy the contract.
To use the core subcontract, create a Contract
structure and implement the Core
for it. The Contract
will be redeployable and will be able to implement other Subcontracts.
use loam_sdk::{soroban_contract, soroban_sdk};
use loam_subcontract_core::{admin::Admin, Core};
pub struct Contract;
impl Core for Contract {
type Impl = Admin;
}
soroban_contract!();
This code generates the following implementation:
struct SorobanContract;
#[contractimpl]
impl SorobanContract {
pub fn admin_set(env: Env, admin: Address) {
set_env(env);
Contract::admin_set(admin);
}
pub fn admin_get(env: Env) -> Option<Address> {
set_env(env);
Contract::admin_get()
}
pub fn redeploy(env: Env, wasm_hash: BytesN<32>) {
set_env(env);
Contract::redeploy(wasm_hash);
}
// Subcontract methods would be inserted here.
// Contract must implement all Subcontracts and is the proxy for the contract calls.
// This is because the Subcontracts have default implementations which call the associated type
}
By specifying the associated Impl
type for Core
, you enable the default Admin
methods to be used (admin_set
, admin_get
, redeploy
). However, you can also provide a different implementation if needed by replacing Admin
with a different struct/enum that also implements IsCore.
Notice that the generated code calls Contract::redeploy
and other methods. This ensures that the Contract
type is redeployable, while also allowing for extensions, as Contract
can overwrite the default methods.