07. Typescript 데코레이터(Decorator)

// 인자가 없을 시엔, 생성자 함수를 선언해줘야
function hello(constructFn: Function) {
    console.log(constructFn);
}

@hello
class Person {
}

function editable(canBeEditable: boolean) {
    return function (target: any, propName: string, description: PropertyDescriptor) {
        description.writable = canBeEditable;
    }
}

class Person {
    @editable(false)
    hello() {
        console.log('hello');
    }
}

const p = new Person();
p.hello(); // hello
p.hello = function () {
    console.log('world');
}
p.hello(); // hello

function writable(canBeWritable: boolean) {
    return function (target: any, propName: string): any {
        return {
            writable: canBeWritable
        };
    }
}

class Person {
    @writable(false)
    name: string = "junho";
}

const p = new Person();
console.log(p.name); // junho
p.name = 'dd'; // error!

function printInfo(target: any, methodName: string, paramIndex: number) {
    console.log(target);
    console.log(methodName);
    console.log(paramIndex);
}

class Person {
    private _name: string;
    private _age: number;

    constructor(name: string, @printInfo age: number) {
        this._name = name;
        this._age = age;
    }

    hello( @printInfo message: string) {
        console.log(message);
    }
}