Macro elrond_wasm::require_old

macro_rules! require_old {
    ($expression:expr, $error_msg:expr) => { ... };
}

Allows us to write Solidity style require!(<condition>, <error_msg>) and avoid if statements.

It can only be used in a function that returns SCResult<_> where _ can be any type.

Example:

fn only_accept_positive_old(&self, x: i32) -> SCResult<()> {
    require_old!(x > 0, "only positive values accepted");
    Ok(())
}