Feature: location payload

[vadymmarkov]

@zenangst @onmyway133 @RamonGilabert

1. We had some discussions about type-safety and magic strings in fragments. We can't really use generics just for optional function parameters. And if we conform to Mappable like in Feature: mappable meta Brick#12 it adds Tailor as a dependency and could lead to many small struct types in the project codebase. My solution here is to add a new property on Location:

public let payload: Any?

Since it's Any we can pass whatever we want and then cast it to the type that we expect:

struct User {
  let firstName: String
  let lastName: String
}

let user = User(firstName: "foo", lastName: "bar")

guard let location = Compass.parse(url, payload: user) else {
  return
}

// ...

if let user = location.payload as? User {
  print("\(user.firstName) \(user.lastName)")
}

2. If you like new payload property, do we need fragments at all? Because you can set [String: AnyObject] dictionary as payload. The only disadvantage is that you have to cast it later:

guard let location = Compass.parse(url, payload: ["foo": "bar"]) else {
  return
}

// ...

if let payload = location.payload as? [String: String] {
  print(payload["foo"])
}

What do you think?

3. From now we can throw errors in Routable that will be caught in Router and handled by a new type called ErrorRoutable. It means we can present some error screen when the route is not found or arguments are invalid.

class ErrorRoute: ErrorRoutable {
  var error: ErrorType?

  func handle(routeError: ErrorType, from currentController: Controller) {
    error = routeError
  }
}

class ThrowableRoute: Routable {
  func navigate(to location: Location, from currentController: Controller) throws {
    throw RouteError.InvalidArguments(location)
  }
}

let router = Router()
let errorRoute = ErrorRoute()

router.errorRoute = errorRoute // errorRoute is an optional var
router.routes["throw"] = ThrowableRoute()
router.navigate(to: Location(path: "throw"), from: UIViewController())

print(errorRoute.error) // RouteError.InvalidArguments

[zenangst]

1. Magic strings bad! This PR good!
2. Well you kind of have to type-cast things that are optional regardless so I don't really see the harm in that.
3. Oooh, errors! You could hook this up with RavenSwift and so on for debugging purposes. And display a message to the user, this is great!

[vadymmarkov]

@zenangst

1. Does it mean you agree with removing fragments in favour of payload?
2. Is payload a good name for that?

[zenangst]

Yeah payload works, I kinda liked fragments but it is a bit confusing as it is an Android term.... #thanksandroid.

I'm totally for payload 😁

[vadymmarkov]

@zenangst fragments field is officially removed. So I think this PR is ready to merge. And yeah, it's a breaking change again 😄

[zenangst]

[onmyway133]

This is good 🎉
But ErrorRoutable, ThrowableRoute terms sound not very intuitive

[vadymmarkov]

@onmyway133 ThrowableRoute is just a name in my example. ErrorRoutable is a part of public API though. Feel free to suggest a better name 😄

[zenangst]

@onmyway133 any suggestions? otherwise I'll just go ahead and merge this bad-boi

[onmyway133]

@zenangst I think you can go ahead

[zenangst]

AAAA YEAH!