데코레이터 타입 안전성

function sealed(constructor: Function) {
    Object.seal(constructor);
    Object.seal(constructor.prototype);
}

function log(
    target: any,
    propertyKey: string,
    descriptor: PropertyDescriptor
) {
    const original = descriptor.value;
    descriptor.value = function (...args: any[]) {
        console.log(`호출: ${propertyKey}`);
        return original.apply(this, args);
    };
}

@sealed
class Calculator {
    @log
    add(a: number, b: number): number {
        return a + b;
    }
}

const calc = new Calculator();
Calculator.prototype.subtract = function (a: number, b: number) {
    return a - b;
};