[swift-evolution] Add code to super methods.

Sean Heber sean at fifthace.com
Wed Nov 16 16:37:13 CST 2016

That could be kind of neat - perhaps a syntax more like this so that there isn’t another bare keyword:

override(after) func viewDidLoad() {


override(before) func viewDidLoad() {

Which would allow you to specify where your code happens - either before or after the superclass method, essentially. Leaving out before/after would still behave as expected and you’d have to call super yourself (or not):

override func viewDidLoad() {
  // stuff
  // more stuff

A potentially neat thing about this is that you could possibly then impose restrictions on subclasses like so:

final(before) func viewDidLoad() {}

Which could mean that the “before” slot is “final” - therefore you cannot do either of these:

override func viewDidLoad() {}
override(before) func viewDidLoad() {}


> On Nov 16, 2016, at 4:30 PM, Mustafa Sabur via swift-evolution <swift-evolution at swift.org> wrote:
> Hallo,
> I have a very simple suggestion. And I’m not very sure then it haven’t been discussed already, so I’m sorry if that is the case.
> I would like to see the ability to just add code to base methods instead of overriding it and calling supers method. So basically an extension for methods.
> Example:
> Now:
> 	override func viewDidLoad() {
> 		super.viewDidLoad()
> 		// Your code
> 	}
> Suggestion:
> 	addinto func viewDidLoad() {
> 		// Your code
> 	}
> My reasons:
> 1. Its very verbose about your intentions, which fits into Swift style. The thing you actually want is not overriding but appending. 
> 2. You cannot make the mistake of forgetting to call the supers method.
> 3. It open ways to introducing ‘semi-final’ methods, which cannot be override but you still can append to it. 
>     This to make sure your API implementation will always be executed . I’m thinking about a keyword like extendable to specify that you can only add to it.
> 4. Less code.
> I can’t think of any cons... Thought I can imagine that the benefits are quite small and maybe not worth the effort.
> I would like to read some thoughts about this. Thank you!
> Kind regards,
> Mustafa Sabur
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