misskey/packages/backend/src/decorators.ts
2023-02-09 10:50:53 +09:00

42 lines
967 B
TypeScript

// https://github.com/andreypopp/autobind-decorator
/**
* Return a descriptor removing the value and returning a getter
* The getter will return a .bind version of the function
* and memoize the result against a symbol on the instance
*/
export function bindThis(target: any, key: string, descriptor: any) {
let fn = descriptor.value;
if (typeof fn !== 'function') {
throw new TypeError(`@bindThis decorator can only be applied to methods not: ${typeof fn}`);
}
return {
configurable: true,
get() {
// eslint-disable-next-line no-prototype-builtins
if (this === target.prototype || this.hasOwnProperty(key) ||
typeof fn !== 'function') {
return fn;
}
const boundFn = fn.bind(this);
Object.defineProperty(this, key, {
configurable: true,
get() {
return boundFn;
},
set(value) {
fn = value;
delete this[key];
},
});
return boundFn;
},
set(value: any) {
fn = value;
},
};
}