复制一个结构对象

Question

i have to quite similar struct objects. but one includes more values than the other. As the initial is required for KituraKuery methods i can not modify it but require more information for future processing.

my problem is now, that these struct objects look like this:

struct provider: Codable {
    var firstName: String?
    var lastName: String?
    var email:String?
}
extension provider: Model{
    class Persistence {}
}

struct provider2: Codable {
    var firstName: String?
    var lastName: String?
    var email:String?
    var providerCategories: [categories]?
}
extension provider: Model{
    class Persistence {}
}

what i need is basically a smarter way to copy information from provider to provider2.

what i did as of now is i provided an init to provider2 taking provider as input and adding all values to it.

struct provider2: Codable {
    var firstName: String?
    var lastName: String?
    var email:String?
    var providerCategories: [categories]?

    init(provider: provider?) {
        if let provider = provider{
            firstName = provider.firstName
            lastName = provider.lastName
            email = provider.lastName
        }
    }
extension provider: Model{
    class Persistence {}
}

i however believe this is probably the worst way and there are much better and more lean approaches to it.

I tried myself on protocols but could that not really get to work.

Any input would be great :)

Answer 1

You could use extensions for this:

extension provider {
    func asProvider2() -> provider2 {
        return provider2(firstName: firstName, 
                          lastName: lastName, 
                          email: email, 
                          providerCategories: nil)
    }
}

// Then you can use it like this:
let bar = provider(firstName: "foo", lastName: "bar", email: "baz")
let bar2 = bar.asProvider2()

Answer 2

In your approach both Provider and Provider2 struct are tightly coupled to each other. So lets say in future if you want to change Provider struct or you want to initialise Provider2 struct with another struct, then you need to change lot of things. We can solve the problem easily by decoupling both Provider and Provider2 struct

protocol BasicInfo {
    var firstName: String? { get set }
    var lastName: String? { get set }
    var email:String? { get set }
}

protocol Address {
    var address: String? {get set}
}

struct Provider: BasicInfo {
    var firstName: String?
    var lastName: String?
    var email: String?
}

struct Provider2: BasicInfo, Address {
    var firstName: String?
    var lastName: String?
    var email:String?
    var address: String?

    init(basic: BasicInfo, add: String) {
        firstName = basic.firstName
        lastName = basic.lastName
        email = basic.email
        address = add
    }
}

//Below are instances of respective struct
let provider1 = Provider(firstName: "Test1", lastName: "TestLast1", email: "test1@gmail.com")
var provider2 = Provider2(basic: provider1, add: "Germany")

In above code i have two different Struct Provider and Provider2. Provider2 contains more variable than Provider (i have just added a single var to demonstrate). Now lets say in future we don't require Provider to fill Provider2, we have a new struct Provider3 which will fill Provider2 values.

struct Provider3: BasicInfo {
    var firstName: String?
    var lastName: String?
    var email: String?
    var middleName: String? //new property added
}

//Below are instances of respective struct
let provider3 = Provider3(firstName: "Test1", lastName: "TestLast1", email: "test1@gmail.com")
var provider2 = Provider2(basic: provider3, add: "Germany")

As you see there is no changes in struct Provider2, we have just introduce a new struct, create instance of new struct and passed that instance to Provider2 init method.