[swift-evolution] [Proposal] Sealed classes by default

[Leonardo Pessoa]

The proposal was to use "sealed" so why not "opened"? I understand it
may not be common to use "opened" as an adjective but from the
dictionaries I consulted it is possible to.

opened class MyViewController: UIViewController {
       opened func displayMe(_ me: person) { … }
}

On 1 July 2016 at 13:47, John McCall via swift-evolution
<swift-evolution at swift.org> wrote:
> On Jul 1, 2016, at 12:23 AM, Xiaodi Wu <xiaodi.wu at gmail.com> wrote:
> That starts to look an awful lot like a fifth access level just for classes
> (I know you're not proposing one, but it could start to look that way to a
> user). I think there's much to be said for having the word public in front
> of things that are public. Unless, of course, your strawman keyword is a
> much maligned compound word that begins with "public", like
> "publicoverridable".
>
>
> I would also prefer a single keyword if the word implies something about
> accessibility.  "open" does that, although using it here would conflict with
> its potential use on enums unless we required all cases within the defining
> module to be present in the enum declaration rather than extensions.
>
> I don't think we'd ever use a compound keyword that starts with public; we'd
> just separate them and say that the second half can only be present on a
> public declaration, or do this parenthesized syntax.
>
> John.
>
>
> On Fri, Jul 1, 2016 at 01:54 Brent Royal-Gordon <brent at architechies.com>
> wrote:
>>
>> > If we're going to go along those lines, we should just use
>> > public(subclassable) and public(overridable).  We can fall back on those if
>> > necessary; I would just like to continue looking for better alternatives.
>>
>> I would prefer to have a *single* keyword which meant both public and
>> overridable. That would minimize the impact of this feature—instead of
>> writing:
>>
>>         public class MyViewController: UIViewController {
>>                 public func displayMe(_ me: person) { … }
>>         }
>>
>> You'd write (strawman keyword):
>>
>>         openseason class MyViewController: UIViewController {
>>                 openseason func displayMe(_ me: person) { … }
>>         }
>>
>> And then `MyViewController` could be subclassed, and `displayMe`
>> overridden.
>>
>> --
>> Brent Royal-Gordon
>> Architechies
>>
>
>
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