Thread: factory pattern using static

Originally Posted by aghast

Correct.

A factory method is a method that is called to build an instance of a class (or subclass). For this reason, you don't usually call factory methods using a class instance. Rather, you make the factory method a static method and call against the class directly.

Code:

new_instance = instance.factory(args);   // NO!

new_instance = Class::factory(args);    // YES!

To be fair, you could have a factory that creates objects from an instance. Suppose you want to create objects with the same complex set of arguments; you could have an instance that contains the arguments, and then you just have to ask that instance to create a new object for those arguments. For example:

Code:

MyFactory* f = new MyFactory();
// set a bunch of arguments
f
  .setFoo(foo)
  .setBar(bar)
  .setBuzz(buzz);

MyObject* obj = f.newObject();