function re(instance, name, val){
    let _value = val;
    Object.defineProperty(instance, name, {
        get: () => {
            console.log('getter called');
            return _value;
        },
        set: (v) => {
            console.log('setter called');
            return _value = v;
        },
        configurable: true
    });
    return val;
}

class A {
    prop = re(this, 'prop', 456)
}

const a = new A()
console.log(a.prop);
a.prop = 123;
console.log(a.prop);