[swift-evolution] Object declarations

[Thorsten Seitz]

You are right! 
That means can keep the upper case name :-)

-Thorsten 

> Am 11.12.2015 um 23:43 schrieb Marc Knaup <marc at knaup.koeln>:
> 
> The type is still necessary in various locations:
> 
> Generics:
> let x = SomeGenericClass<SingletonObject>
> 
> Type checking:
> let x: Any = SingletonObject
> let x: SingletonObject? = x as? SingletonObject
> 
> Passing the type dynamically:
> func foo(type: Any.Type) { … }
> foo(SingletonObject)
> 
> Since there can only be one instance the "object class" (if it isn't a struct) would be final.
> 
>> On Fri, Dec 11, 2015 at 11:34 PM, Thorsten Seitz <tseitz42 at icloud.com> wrote:
>> 
>>> Am 11.12.2015 um 23:28 schrieb Marc Knaup <marc at knaup.koeln>:
>>> 
>>> Actually it's both - an object and a type. It's an object which describes itself.
>> 
>> If it was a type then I would expect to be able to 
>> - derive a subclass from it
>> - use it as type in variable or parameter declarations
>> 
>> I don't think either makes sense, or does it?
>> 
>>> Btw. I have the same problem with enum cases. They're values so why are they uppercase?
>> 
>> Hmm, good point. Guess I'm just used to it :-)
>> 
>> -Thorsten
>> 
>>>> On Fri, Dec 11, 2015 at 11:25 PM, Thorsten Seitz <tseitz42 at icloud.com> wrote:
>>>> I like it. Just a minor suggestion: as an object is a value and not a type it should have a name starting with lower case, i.e.
>>>> 
>>>> object globalResource { ... }
>>>> 
>>>> -Thorsten 
>>>> 
>>>>> Am 11.12.2015 um 23:07 schrieb Marc Knaup via swift-evolution <swift-evolution at swift.org>:
>>>>> 
>>>>> Hey guys,
>>>>> 
>>>>> I am working on a proposal which touches (and could even partially depend on) another interesting concept which I think would be a great addition for Swift.
>>>>> 
>>>>> Object declarations could be a way to declare a class or struct with exactly one instance. They are perfect for singletons, anonymous subclasses and to anonymously implement a protocol.
>>>>> 
>>>>> Here some examples how it could look like:
>>>>> 
>>>>> // singleton
>>>>> object GlobalResource {
>>>>>     func doSomething() { … }
>>>>> }
>>>>> 
>>>>> let resource = GlobalResource
>>>>> 
>>>>> // could all be the same
>>>>> resource.doSomething()
>>>>> GlobalResource.doSomething()
>>>>> GlobalResource.Type.doSomething()
>>>>> 
>>>>> 
>>>>> // anonymous subclass
>>>>> class ViewController: UIViewController {
>>>>> 
>>>>>     override func loadView() {
>>>>>         view = object: UIView {
>>>>>             // configure view
>>>>>         }
>>>>>     }
>>>>> }
>>>>> 
>>>>> 
>>>>> // anonymous protocol implementation
>>>>> protocol TapHandler {
>>>>>     func handleTap()
>>>>> }
>>>>> 
>>>>> view.tapHandler = object: TapHandler {
>>>>>     func handleTap() {
>>>>>         // …
>>>>>     }
>>>>> }
>>>>> 
>>>>> 
>>>>> Kotlin is an example for a a modern language which uses this concept:
>>>>> https://kotlinlang.org/docs/reference/object-declarations.html
>>>>> 
>>>>> 
>>>>> What do you think about such an addition?
>>>>> 
>>>>> _______________________________________________
>>>>> swift-evolution mailing list
>>>>> swift-evolution at swift.org
>>>>> https://lists.swift.org/mailman/listinfo/swift-evolution
> 
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