Crate casper_contract

A Rust library for writing smart contracts on the Casper Platform.

no_std

By default, the library is no_std, however you can enable full std functionality by enabling the crate’s std feature.

Example

The following example contains session code which persists an integer value under an unforgeable reference. It then stores the unforgeable reference under a name in context-local storage.

#![no_std]

use casper_contract::{
    contract_api::{runtime, storage},
};
use casper_types::{Key, URef};

const KEY: &str = "special_value";
const ARG_VALUE: &str = "value";

fn store(value: i32) {
    // Store `value` under a new unforgeable reference.
    let value_ref: URef = storage::new_uref(value);

    // Wrap the unforgeable reference in a value of type `Key`.
    let value_key: Key = value_ref.into();

    // Store this key under the name "special_value" in context-local storage.
    runtime::put_key(KEY, value_key);
}

// All session code must have a `call` entrypoint.
#[no_mangle]
pub extern "C" fn call() {
    // Get the optional first argument supplied to the argument.
    let value: i32 = runtime::get_named_arg(ARG_VALUE);
    store(value);
}

Writing Smart Contracts

Support for writing smart contracts are contained in the contract_api module and its submodules.

Modules

contract_api

Contains support for writing smart contracts.

ext_ffi

Contains low-level bindings for host-side (“external”) functions.

unwrap_or_revert

Home of UnwrapOrRevert, a convenience trait for unwrapping values.

Statics

ALLOC

An instance of WeeAlloc which allows contracts built as no_std to avoid having to provide a global allocator themselves.