Should empty parentheses for super-constructors be required?

I’m wondering if the () must be required in the second line of this example:

open class Base
class Derived : Base()

I can declare the base class without brackets, it would be nice if the same were true for the inheritance relationship.

The parentheses indicate which of the base types of your class is a class (requiring parentheses) and which is an interface (where no parentheses are allowed).

Sorry, should have given more context.

I do know about this distinction. BUT:

  • It is impossible to instantiate interfaces, thus I can never call the constructor for them anyway. If I really want to know more details about the base I can always press CTRL+J to show quick java doc or CTRL+H to show hierarchy.
  • I believe I read somewhere that one of the reasons for the Derived : Base syntax was to do away with the distinction between extends and implements that you have in Java. I feel like requiring brackets sneaks this distinction back in

I would find it more consistent if I could get rid of the brackets (or always require them class declarations). Just a thought :slight_smile:

I’d like to see the () removed too, it’s just extra noise (make it optional so it doesn’t break anything).

The trade-off here is

  • extra parentheses, versus
  • knowledge of which supertype if a class.

Not so easy to tell which is better, really, so this cleasly goes under the “bikeshedding” category :slight_smile:

If you think of a constructor call, this syntax makes sense. A constructor is more or less a function and you have to write parenthesis when calling parameterless functions, too.


For completeness, this variant should be included in the discussion:

open class Base

class Derived : Base {
    constructor() : super()
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