typescriptでメタプログラミング ProxyとReflect

proxy.ts

function proxy(obj: any) {
    return new Proxy(obj, {
        set: function (target, property, value, receiver) {
            console.log(`[proxy.set] property=${String(property)} value=${value}`);
            return Reflect.set(target, property, value, receiver);
        },
        get: function (target, property, receiver) {
            const value = Reflect.get(target, property, receiver);
            if (typeof value !== "function") {
                console.log(`[proxy.get] property=${String(property)}`);
                return value;
            } else {
                const func = value as Function;
                const func_proxy = new Proxy(func, {
                    apply: function (target, thisArg, argumentsList) {
                        console.log(
                            `[proxy.apply] target=${String(
                                property
                            )} argumentsList=${argumentsList}`
                        );
                        return Reflect.apply(target, thisArg, argumentsList);
                    },
                });
                return func_proxy;
            }
        },
    });
}

class Foo {
    bar;
    constructor(n: number) {
        this.bar = n;
    }
    baz(n: number) {
        console.log(`bar ${n}`);
    }
}

const x = (foo: Foo) => {
    console.log(foo.bar);
    foo.bar = 2;
    foo.baz(3);
}

x(new Foo(1));
x(proxy(new Foo(10)));