rhai/examples/event_handler_js/script.rhai

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2022-01-16 15:45:25 +01:00
// Implementation of the Event Handler With State Pattern - JS Style
/// Initialize user-provided state.
fn init() {
// Can detect system-provided default states!
// Add 'bool_state' as new state variable if one does not exist
if !("bool_state" in this) {
this.bool_state = false;
}
// Add 'value' as new state variable (overwrites any existing)
this.value = 0;
// Can also add OOP-style functions!
this.log = |x| print(`State = ${this.value}, data = ${x}`);
}
/// 'start' event handler
fn start(data) {
if this.bool_state {
throw "Already started!";
}
if this.value <= 0 {
throw "Conditions not yet ready to start!";
}
this.bool_state = true;
this.value += parse_int(data);
// Constant 'MY_CONSTANT' in custom scope is also visible!
print(`MY_CONSTANT = ${MY_CONSTANT}`);
}
/// 'end' event handler
fn end(data) {
if !this.bool_state {
throw "Not yet started!";
}
if this.value > 0 {
throw "Conditions not yet ready to end!";
}
this.bool_state = false;
this.value = parse_int(data);
}
/// 'update' event handler
fn update(data) {
let data = parse_int(data);
this.value += data;
this.log(data);
}