es2015-callable.js

es2015-callable.js

/**
 * Callable objects in ES2015.
 * by Dmitry Soshnikov <[email protected]>
 * MIT Style License
 */

class Callable extends Function {
  constructor() {
    super('(' + Callable.prototype.__call__ + ')();');
    return this.bind(this);
  }

  // Notice, this method cannot have free variables,
  // because functions, created by the `Function`
  // constructor aren't actual closures (they capture
  // only global environment).
  __call__() {
    return this.method();
  }

  method() {
    console.log(1);
  }
}

var c = new Callable();

c(); // 1

// or simply :P

c.__call__();

// Alternative way to create a callable object, is to use Proxies,
// but even then, a target should be a callable object as well.