use fuel_types::ContractId;
pub struct Log {
    pub contract_id: ContractId,
    pub ra: u64,
    pub rb: u64,
  • A Log receipt is generated when calling log() on a non-reference types in a Sway contracts.
    • Specifically bool, u8, u16, u32, and u64.
  • The ra field includes the value being logged while rb may include a non-zero value representing a unique ID for the log instance.
  • Read more about Log in the Fuel protocol ABI spec

You can handle functions that produce a Log receipt type by adding a parameter with the type abi::Log.

fn handle_log(log: abi::Log) {
  // handle all functions that produce a log receipt