Allergies Problem - Swift Enum about swift HOT 11 CLOSED

@AJEzk My guess is that it just kind of happened that way.

@marianaiam What's Gen's GitHub? I feel like between the two of you, you might have an opinion on this.

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This was a tricky one because the cleanest solution is either a struct that conforms to OptionSetType or, as you suggested, an enum with integer raw values. I haven't looked at Allergies in a while but I seem to remember it being tough to design an API that allowed for either solution.

In writing the tests, I tried to avoid requiring a certain approach. I'm fairly sure that's why this one didn't require enum. I haven't looked too deeply at this one since Swift 2, so if you can think of a way to allow for OptionSetType or enum, I'd love the pull request.

If you can't think of a way to allow either solution, submit a pull request anyway. We're short on enumerations and I think it would help to have a few more.

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I've thought about this some more and I'm having a lot of trouble figuring out a really clean way to solve this problem with enums that didn't require some tricky handling. You could store the list of allergies in a Set<Allergies> and use .contains() to check, but then how would we encapsulate that behavior without leaking the implementation? Maybe use a factory? Am I missing an obvious solution?

I'm starting to think that sticking with OptionSetType really is the best solution, but I also would like more Enums in the Swift problem set. Maybe we can find another problem that could use enums, or just write a new one entirely?

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https://gist.github.com/masters3d/5e91105d2ef994c4211e
This could allow struct or enum solutions.

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Clever. I was hung up on instantiating an allergy set, but your static method sidesteps the issue nicely. I like it.

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I was thinking something very similar to @masters3d.

The tests would look something like this:

class AllergiesTest: XCTestCase {

    func testBob() {

        let patient = Patient(34)

        XCTAssertTrue(patient.hasAllergy(Allergies.Peanuts), "Bob is allergic to peanuts")
        XCTAssertTrue(patient.hasAllergy(Allergies.Chocolate), "Bob is allergic to chocolate")
        XCTAssertFalse(patient.hasAllergy(Allergies.Cats),  "Bob is not allergic to cats")
    }

    func testEggsNcats() {

        let patient = Patient(129)

        XCTAssertTrue(patient.hasAllergy(Allergies.Eggs))
        XCTAssertTrue(patient.hasAllergy(Allergies.Cats))
        XCTAssertFalse(patient.hasAllergy(Allergies.Chocolate))

    }

    func testNone() {
        let patient = Patient(0)

        XCTAssertFalse(patient.hasAllergy(Allergies.Pollen))
    }

    func testAll() {

        let allInt =  UInt(Array(0...7).reduce(0){ return ($0 | (1 << $1)) })
        let patient = Patient(allInt)

        XCTAssertTrue(patient.hasAllergy(Allergies.Eggs))
        XCTAssertTrue(patient.hasAllergy(Allergies.Peanuts))
        XCTAssertTrue(patient.hasAllergy(Allergies.Shellfish))
        XCTAssertTrue(patient.hasAllergy(Allergies.Strawberries))
        XCTAssertTrue(patient.hasAllergy(Allergies.Tomatoes))
        XCTAssertTrue(patient.hasAllergy(Allergies.Chocolate))
        XCTAssertTrue(patient.hasAllergy(Allergies.Pollen))
        XCTAssertTrue(patient.hasAllergy(Allergies.Cats))

    }
}

A sample solution would look like this:

enum Allergies: UInt {
        case Eggs = 1
        case Peanuts = 2
        case Shellfish = 4
        case Strawberries = 8
        case Tomatoes = 16
        case Chocolate = 32
        case Pollen = 64
        case Cats = 128
}

struct Patient {
    let score: UInt

    init(_ score: UInt) {
        self.score = UInt(score)
    }

    func hasAllergy(allergen: Allergies) -> Bool {
        return allergen.rawValue & score == allergen.rawValue ? true : false
    }
} 

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Also you can drop the enum name from the test case
hasAllergy( .Pollen)
The compiler is able to tell which enum type it takes so it doesn't enforce the name to be included.

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Thanks @AJEzk for the PR!

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Yes! My first open source contribution! :)

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Nice!

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@AJEzk The first of many, I hope! Great work!

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