装饰器之 get / set 装饰器

前置知识：

class b {
  val = 999;
  get bv() {
    return this.val;
  }
  set bv(v) {
    this.val = v;
  }
}
let ins = new b();
console.log(ins.bv);  //999
ins.bv = 888;
console.log(ins.bv);   //888
 

?类可以在一个方法前加 get / set 设置该方法的行为；

而 get / set 装饰器就是用来替代原来的 get/set 方法内的逻辑；

class b {
  val:any = 999;
  @myGet
  get bv() {
    return this.val;
  }
  set bv(v) {
    this.val = v;
  }
}
function myGet(value: any, context: ClassGetterDecoratorContext){
  return function(){
     return '替换原来的get'
  }
}
let ins = new b();
console.log(ins.bv); //'替换原来的get'

class b {
  val: any = 999;
  @mySet("替代自身set")
  set bv(v: any) {
    this.val = v;
  }
  get bv() {
    return this.val;
  }
}
function mySet(setVal: string) {
  return function (value: any, context: ClassSetterDecoratorContext) {
    return function (this: any) {
      this.val = setVal;
    };
  };
}
let ins = new b();
ins.bv = 888;
console.log(ins.bv); //替代自身set