[swift-evolution] Feature Idea: Namespace keyword for grouping related internal entities without resorting to non-initializable structs.

[T.J. Usiyan]

+1 from me.

This has apparently become my schtick but the structs are definitely
initializable. Make them enums with no case to guard against initialization.

``` swift
extension AreaOfConcern {
    init() {}
}
```

On Sat, Feb 20, 2016 at 9:55 AM, Jared Sinclair via swift-evolution <
swift-evolution at swift.org> wrote:

> *TL;DR*
>
> I’d like to be able to group related internal entities within a namespace
> declaration, without having to fake it with non-initializable structs:
>
> internal namespace AreaOfConcern {
>   let SomeString = “SomeString”
>   let SomeInt = 42
>   func checkSomething() -> Bool {…}
> }
>
>
> *Rationale*
>
> Often within a module I find myself wanting to group related *internal*
> entities together within a namespace. Free functions and constants are a
> good example:
>
> internal let SomeString = “SomeString”
> internal let SomeInt = 42
> internal func checkSomething() -> Bool {…}
>
> So are thematically-related structs:
>
> internal struct CreateANote: Endpoint {
>   // ...
> }
> internal struct UpdateANote: Endpoint {
>   // ...
> }
> internal struct DeleteANote: Endpoint {
>   // ...
> }
>
> The best way to approximate this currently is to wrap them in a struct,
> like:
>
> internal struct AreaOfConcern {
>   static let SomeString = “SomeString”
>   static let SomeInt = 42
>   static func checkSomething() -> Bool {…}
> }
>
> or for thematically-related structs, to enable tidy usage for the callers:
>
> internal struct NoteEndpoints {
>   struct Create: Endpoint {
>     // ...
>   }
>   struct Update: Endpoint {
>     // ...
>   }
>   struct Delete: Endpoint {
>     // ...
>   }
> }
>
> let endpoint = NoteEndpoints.Create(text: String, …)
>
> This solution is somewhat awkward because AreaOfConcern and NoteEndpoints are
> not really being used as structs so much as an informal namespaces. To
> communicate this to internal users (and to discourage them from trying to
> initialize these wrapper structs), you can give them private initializers
> (which is even more awkward, but helpful):
>
> internal struct AreaOfConcern {
>      static let SomeString = “SomeString”
>      static let SomeInt = 42
>      static func checkSomething() -> Bool {…}
>
>      private init()
> }
>
> It would be preferable if there was another keyword, perhaps namespace,
> that could be used as follows:
>
> internal namespace NoteEndpoints {
>   struct Create: Endpoint {
>     // ...
>   }
>   struct Update: Endpoint {
>     // ...
>   }
>   struct Delete: Endpoint {
>     // ...
>   }
> }
>
> The namespace keyword would follow all the same scope and dot-notation
> rules as a structs, but would not be initializable.
>
> --
> Jared Sinclair
> Sent with Airmail
>
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> swift-evolution mailing list
> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution
>
>
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