Simple implementation of an async value in swift.
func getUserFromInternet() -> Eventual<User> {
let r = Resolver<User>()
networkClient.get("whatever") { json in
// do your json -> domain object
let user: User = userFromJSON(json)
r.resolve(user)
}
return r.eventual
}let eventualUser = getUserFromInternet()
eventualUser.finally { user in
// now you have a user!
}NOTE Eventual does not care about threading/queuing, so you need to manage where you do work. Handlers will be called from whatever context the Eventual is resolved in. Need to be on the main thread after getting a value? Use one of the wealth of options in Foundation.
You can also chain without losing type safety:
let nameEventual = eventualUser.then { user in user.firstName }
nameEventual.finally { name in print(name) }Or chain with other async operations:
func getReposForUser(user: User) -> Eventual<[Repo]> { ... }
let eventualRepos = getUserFromInternet().then{ user in getReposForUser(user) }join:
join(Eventual("hi"), Eventual(23)).finally { tuple in
print(tuple.0) // hi
print(tuple.1) // 23
}lift:
Convert functions from operating on concrete types to work on eventuals instead:
func add(lhs: Int, rhs: Int) -> Int {
return lhs + rhs
}
// add is Int, Int -> Int
let liftedAdd = lift(add)
// liftedAdd is Eventual<Int>, Eventual<Int> -> Eventual<Int>
// the final value will be resolved as the addition of the two values once they resolveUnsafeGetEventualValue:
This method is intended to help while testing, when you expect an Eventual to be resolved in a particular way. Use of this in production code is heavily discouraged as it sidesteps much of the point of the tool.
func testResolvesAfterWork() {
let workDoer = WorkDoer()
let eventual = workDoer.work()
XCTAssertNil(UnsafeGetEventualValue(eventual))
workDoer.finishWorking()
XCTAssertEqual(UnsafeGetEventualValue(eventual), "work finished!")
}
React
Typescript
Django
Laravel
Facebook
Microsoft
Google
Alibaba
D3
Tencent