rhai/examples/event_handler_main/script.rhai
2022-08-10 13:15:34 +08:00

57 lines
1.3 KiB
JavaScript

//! Implementation of the Event Handler With State Pattern - Main Style
/// Initialize user-provided state (shadows system-provided state, if any).
fn init() {
// Add 'bool_state' and 'value' as new state variables
let bool_state = false;
let value = 0;
// Constants can also be added!
const EXTRA_CONSTANT = "hello, world!";
}
/// Without 'OOP' support, the can only be a function.
fn log(value, data) {
print(`State = ${value}, data = ${data}`);
}
/// 'start' event handler
fn start(data) {
if bool_state {
throw "Already started!";
}
if value <= 0 {
throw "Conditions not yet ready to start!";
}
bool_state = true;
// Constants 'MY_CONSTANT' and 'EXTRA_CONSTANT'
// in custom scope are also visible!
print(`MY_CONSTANT = ${MY_CONSTANT}`);
print(`EXTRA_CONSTANT = ${EXTRA_CONSTANT}`);
value += parse_int(data);
}
/// 'end' event handler
fn end(data) {
if !bool_state {
throw "Not yet started!";
}
if value > 0 {
throw "Conditions not yet ready to end!";
}
bool_state = false;
value = parse_int(data);
}
/// 'update' event handler
fn update(data) {
let data = parse_int(data);
value += data;
// Without OOP support, can only call function
log(value, data);
}