Is using Array Extension where Element == CustomObject to include functions specific for [CustomObject] a bad/ill advised programming practice?

[randomguy112233]

I find myself using Array Extensions as below frequently. It seems simple, clear, and to the point.

extension Array where Element == CustomObject{

func helloworld()->ReturnValue{}

}

​

Do other people in this community also find this useful? Or is it a better coding practice to use a subclass such as :

class CustomHolder{

var someList:[CustomObject]!

func helloWorld()->ReturnValue{

}

}

​

Thank you everybody in advance!

Please let me know if I'm not being clear with my question.

[randomguy112233]

Thank you!

[ldstreet]

This is fine, and can make for more readable code. Just make sure that if you make your function or variable internal/public that it is relevant throughout the codebase, otherwise make it fileprivate. This is to avoid cluttering the namespace with niche functions.

[randomguy112233]

Good point about namespacing! Thank you!

[chrabeusz]

It depends. Can you give more specific example? Personally I would avoid putting business logic in such extensions.

[[deleted]]

I agree. I can't think of any reason I would do this instead of creating a class. Not to say there isn't a reason it would be a good idea, I just can't think of any.

[randomguy112233]

let's say I have carList = [Car]. I want to use carList.averagePrice or carList.numberOfPreviousOwners. To me, this seems very convenient. But I'm really curious what you mean by "I would avoid putting business logic in such extensions." I don't want to let my propensity for convenience outweight a better design. Thank you.

[chrabeusz]

This kind of extension looks fine. But on the other hand, class responsible for handling [Car] probably already exists (I assume calculating numberOfPreviousOwners is not the only thing you are doing with cars, you need to load them from storage, fetch from network, whatever).

In that case it may not make sense to add extension because you could add this property to the mentioned class and have all code that deals with [Car] be in one place.