function writable(canBeWritable:boolean){

    return function(target:any, propName:string):any{

        console.log(target);

        console.log(propName);

        return{

            writable:canBeWritable,

        };

    }

}

class Person{

    @writable(false)

    name:string = 'kim';

    constructor(){

        console.log('new Person()');

    }

}

const p= new Person();

console.log(p.name);

function editable(canBeEditable : boolean){

    return function(target:any, propName:string, description:PropertyDescriptor){

        console.log(target);

        console.log(propName);

        console.log(description);

        description.writable = canBeEditable;

    }

}

class Person{

    constructor(){

        console.log('new Person()');

    }

    @editable(false)

    hello(){

        console.log('hello');

    }

}

const p= new Person();

p.hello();

p.hello=function(){

    console.log('world');

}

p.hello();

프로퍼티에 적용

function firstDecorator(target, name){

    console.log('firstDecorator');

    console.log(target,name);

}

class Person{

    @firstDecorator

    job:'dancer';

    @firstDecorator

    age:30;

}

const p=new Person();

=================================

인스턴스 생성전에 decorator 전부 발동됨(미리 준비)

객체 생성문 없어도 준비됨.

인스턴스 생성하면 발동된것을 박는거임

function firstDecorator(param){

    console.log('factory');

    return function(target,name){

        console.log('decorator');

    }

}

class SomeClass{

    @firstDecorator(123)

    prop='a';

}

console.log('인스턴스 생성 전');

console.log(new SomeClass());

interface Person{

    name:string;

    age:number;

}

function getProperty<T,K extends keyof T>(obj:T, key:K):T[K]{

    return obj[key];

}

function setProperty<T,K extends keyof T>(obj:T, key:K, value:T[K]):void{

    obj[key] = value;

}

const person:Person = {

    name:'gibeom',

    age:35,

}

console.log(getProperty(person,'name'));

console.log(getProperty(person,'age'));

setProperty(person,'name','modified name');

console.log(getProperty(person,'name'));

console.log(getProperty(person,'age'));

class Person<T, K>{

    private _name:T;

    private _age:K;

    constructor(name:T,age:K){

        this._name=name;

        this._age=age;

    }

}

new Person('kim',30); <- 여기서 객체의 타입을 정해버림

제한을 둔다

class Person<T extends string|number>{

    private _name:T;

    constructor(name:T){

        this._name=name;

    }

}

new Person('aa');

new Person(22);

class Person<T>{

    private _name:T;

    constructor(name:T){

        this._name=name;

    }

}

const kim = new Person('gibeom');

const age = new Person(123);

console.log(kim);

console.log(age);

any 쓰지말고 제네릭 사용하면 좋음.

function helloString(message:string):string{

    return message;

}

function helloNumber(message:number):number{

    return message;

}

function hello<T>(message:T):T{

    return message;

}

hello("a");

hello(123);

function anyFn(param:any):any{

    return param;

}

String(anyFn("Aa")).substr;

any 를 쓰면 타입을 일일이 바꿔서 함수사용