An example of a Constructor Composer for my How to Grok a Higher Order Class article

extend_constructor_composer.js

export default function(methodComposer) {
  return ClassToCompose => {
    const proto = ClassToCompose.prototype;
    return class extends ClassToCompose {
      constructor() {
        super(...arguments);
        for (const prop of Object.getOwnPropertyNames(proto)) {
          const method = proto[prop];
          const {configurable, writable} = Object.getOwnPropertyDescriptor(proto, prop);
          if (method instanceof Function &&
              // we can't change non configurable or writable methods
              configurable && writable &&
              // touching the constructor won't help us here, as we're modifying an existing instance
              method !== ClassToCompose) {
            this[prop] = methodComposer(proto[prop], prop);
          }
        }
      }
    };
  };
}

extend_constructor_composer_example.js

import constructorComposer from './extend_constructor_composer';

/**
* We'll use the same ComposableBaseClass class and verbosify function from before
*/


/**
* Constructor Composite Example
*/

// create verbosified factory creator - this would only be done once per function, so it would only be used once for the 'verbosify' function in your codebase
const createVerbosifiedConstructorClass = constructorComposer(verbosify);
// create verbosified factory of the composable class - this would be used per class you wish to attach the verbose beahviour to
const VerbosifiedConstructorComposedClass = createVerbosifiedConstructorClass(ComposableBaseClass);

// usage of factory every time you want a verbose instance of ComposableBaseClass
myVerboseInstance = new VerbosifiedConstructorComposedClass();