Why need to 'initialize' contract in AMM github example?

[carlos]

I initially copied this code from the sway examples github:

fn initialize(exchange_bytecode_root: ContractId) {
        require(storage.exchange_bytecode_root.read().is_none(), InitError::BytecodeRootAlreadySet);
        storage.exchange_bytecode_root.write(Option::Some(exchange_bytecode_root.into()));
    }

However i get the error:

“” ^^^^ No method named “read” found for type “Option”.“”"

Could someone explain me this error and maybe even more important. Explain the need to initialise the contract here? I dont see it in other examples?

[david]

What version of forc are you using? The error you mentioned seems to be the result of using an older version of Fuel & Sway.

As for why there’s an initializer: Sway doesn’t have constructors like Solidity. If you need to initialize storage slots, there must be an initialize function.

[carlos]

I am using forc 0.37.3 and fuel-core 0.17.11

[sandusky]

So basically you are trying to run newer code with an older compiler

Please run

 fuelup toolchain install latest

and then

fuelup default latest

Let me know if it works

[carlos]

@sandusky

fuelup default latest

Thanks @sandusky and @david That was it.