[swift-evolution] custom attribute in userland.

CustomAttributes.swift

// Example of custom attribute


@attribute("route")
struct Route {
    var route: String
    var name: String?

    init(route: String) {
        self.route = route
    }
}

@attribute("method")
struct Method {
    var verb: String

    init(verb: String) {
        self.verb = verb
    }
}

struct CourseController {
    
    @route("/courses/", name="toto")
    @method("GET")
    func listAction(request: Request) -> Response {
        return Response(200, "Hello World")
    }
}

let app = Application()

app.register(CourseController())

app.run(8080)

// other example of custom attribute 
@mappable
class ArticleEntity {

    @field("article_id")
    var id: Int

    @field("article_name")
    var name: String
}