[swift-evolution] [Discussion] Enforcing Calling Super

[Matthew Johnson]

Sent from my iPad

> On Feb 25, 2016, at 1:17 PM, Jean-Daniel Dupas via swift-evolution <swift-evolution at swift.org> wrote:
> 
> 
>> Le 25 févr. 2016 à 16:47, Jeremy Pereira via swift-evolution <swift-evolution at swift.org> a écrit :
>> 
>> 
>>> On 17 Feb 2016, at 22:26, Kyle Sherman via swift-evolution <swift-evolution at swift.org> wrote:
>>> 
>>> Thanks for the replies.
>>> 
>>> Kenny: After thinking about it more, discussing with Peter, and looking Haravikk’s comments, I think the best thing would be for this to be a warning as suggested. I respectfully disagree that as a library creator you would not be able to know that a call to super should be required.
>> 
>> I disagree. You can’t possibly know all the use-cases in which your class might be subclassed. 
>> 
>> In particular, it is absurd to enforce having the call to super as the first or last line of the method. That would stop me doing things like this:
>> 
>>   override func viewDidLoad()
>>   {
>>       print(“About to run super.viewDidLoad()”)
>>       super.viewDidLoad()
>>       print(“Finished super.viewDidLoad()”)
>>   }
>> 
>> Then there’s the perfectly reasonable case like this:
>> 
>>   override func viewDidLoad()
>>   {
>>       functionThatCallsSuperViewDidLoad()
>>   }
>> 
>> Why shouldn’t I be allowed to do that?
> 
> +1 with your concern. I’d be curious to see a single real world use case where enforcing first or last is required.

I posted several examples from Apple frameworks in an old thread about this.  You might want to look for that message in the archives.

> 
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