4 ms·

In Smalltalk, how would how would the consumer be given differing implementations of this "new" method? And wouldn't that just make the "new" method a factory?

riffraff 7y ago
yes it would be a factory, the difference being that you don't have to use a different syntax (`Klass.build/new Klass` would be `Klass new` in both cases)
matheusmoreira 7y ago
> In Smalltalk, how would how would the consumer be given differing implementations of this "new" method? Classes can simply override that method. The default implementation of new is: ^ self basicNew initialize And basicNew is a method that allocates and returns an instance of the receiver. So a custom implementation can easily change self to some other class, chain more messages or replace initialize with something else, add more logic before an object is returned and so on. > And wouldn't that just make the "new" method a factory? Smalltalk actually predates the discovery of object-oriented design patterns by a couple of decades so it's the factory methods that are like the new method. For some reason language designers turned it into a magic keyword and people rediscovered the fact that methods are better.
- LgWoodenBadger 7y ago
  If my BubbleMachine currently makes SoapBubbles, but I want it to be able to make GumBubbles as well, who, out of those three, is responsible for overriding the “new” method to create GumBubbles instead of SoapBubbles?
  - spankalee 7y ago
    A Bubbles class, which is basically the same as a factory. I don't see a huge difference in practice myself.
  - matheusmoreira 7y ago
    Are these all subclasses of a Bubbles class? I think that'd be the natural place for a custom new method that figures out which subclass to construct based on the parameters. In Java, an interface could have a static method that returns concrete implementations of itself.
    - scroot 7y ago
      It's even better. If it's just making stuff, you don't even need `BubbleMachine` if you have the `Bubbles` base class. You can add creation method on the class side of `Bubbles` like so: `Bubbles class >> #newGum` ^ GumBubbles new `Bubbles class >> #newSoap` ^ SoapBubbles new The difference here is that the base class still serves as a true base: it will have all the common functionality for various kinds of bubbles

riffraff 7y ago

yes it would be a factory, the difference being that you don't have to use a different syntax (`Klass.build/new Klass` would be `Klass new` in both cases)

matheusmoreira 7y ago

> In Smalltalk, how would how would the consumer be given differing implementations of this "new" method? Classes can simply override that method. The default implementation of new is: ^ self basicNew initialize And basicNew is a method that allocates and returns an instance of the receiver. So a custom implementation can easily change self to some other class, chain more messages or replace initialize with something else, add more logic before an object is returned and so on. > And wouldn't that just make the "new" method a factory? Smalltalk actually predates the discovery of object-oriented design patterns by a couple of decades so it's the factory methods that are like the new method. For some reason language designers turned it into a magic keyword and people rediscovered the fact that methods are better.

LgWoodenBadger 7y ago
If my BubbleMachine currently makes SoapBubbles, but I want it to be able to make GumBubbles as well, who, out of those three, is responsible for overriding the “new” method to create GumBubbles instead of SoapBubbles?
- spankalee 7y ago
  A Bubbles class, which is basically the same as a factory. I don't see a huge difference in practice myself.
- matheusmoreira 7y ago
  Are these all subclasses of a Bubbles class? I think that'd be the natural place for a custom new method that figures out which subclass to construct based on the parameters. In Java, an interface could have a static method that returns concrete implementations of itself.
  - scroot 7y ago
    It's even better. If it's just making stuff, you don't even need `BubbleMachine` if you have the `Bubbles` base class. You can add creation method on the class side of `Bubbles` like so: `Bubbles class >> #newGum` ^ GumBubbles new `Bubbles class >> #newSoap` ^ SoapBubbles new The difference here is that the base class still serves as a true base: it will have all the common functionality for various kinds of bubbles