从一个类调用方法时从另一个类调用方法

Question

I have two classes: first on checks that file exists and it's valid; second one make some stuff with that file:

class Validator {
   constructor(){
      this.file = './file.json';
   }
   check(){ ... }
}

class Modificator {
   action1(){ ... }
   action2(){ ... }
}

What I want is the method from first class automatically calls inside each method from the second class. It's a bit tricky stuff, but I'm really don't want to do it manually, like so:

class Validator {
   constructor(){
      this.file = './file.json';
   }
   static check(){ ... }
}

class Modificator {
   action1(){ 
      let status = Validator.check();
      ...
   }
   action2(){ 
      let status = Validator.check();
      ...
   }
}

Answer 1

1. By using a wrapper

 class Validator { static check () {console.log('checked')} static checkCbk (fn) { return _ => { this.check() //then callback fn() } } } class Modificator { //via public instance field action1 = Validator.checkCbk(function () { console.log('mod::action1') }) } //or by prototype Modificator.prototype.action2 = Validator.checkCbk(function(){ console.log('mod::action2') }) var m = new Modificator() m.action1() m.action2()

However notice that if you were to subclass Modificator , you could forget to rewrap your methods...

2. By making a contract

More commonly by making a contract and delegating to implem if contract is fulfilled.

This way you don't have to worry when extending since check is made in base class anyway.

 class Validator { static check () {console.log('checked')} } class Contract { action1 () { Validator.check() this._action1() } } class M2 extends Contract { _action1 () { console.log('mod2::action1') } } var m = new M2() m.action1()