generic type check decorator

Person2.ts

import 'reflect-metadata';
import { ui } from 'tabris';

function check(prototype: object, property: string) {
  const sym = Symbol();
  const constr = Reflect.getMetadata('design:type', prototype, property);
  Object.defineProperty(prototype, property, {
    enumerable: true,
    set(value: any) {
      if (!(value instanceof constr) && (typeof value !== constr.name.toLocaleLowerCase())) {
        throw  new  Error(`Failed to set "${property}": ${constr.name} expected, got ${typeof  value}`);
      }
      this[sym] = value;
    },
    get() {
      return this[sym];
    }
  });
}

class Person {  
  @check public name: string;
  @check public married: boolean;
}

const jack = new Person();

try {
  Object.assign(jack, JSON.parse(
    '{"name": "Jack Bauer", "married": "yes"}'
  )); // Error: Failed to set "married": Boolean expected, got string
} catch(ex) {
  console.error(ex);
} 

try {
  Object.assign(jack, JSON.parse(
    '{"name": "Jack Bauer", "married": true}'
  )); 
} catch(ex) {
  console.error(ex);
} 

ui.contentView.append(<textView>{jack.name + ' is married: ' + jack.married}</textView>);