Capturing references to initializers?


(Austin Zheng) #1

Hello Swift users,

I have a question about capturing references to initializers. You can do
the following right now:

struct Foo {
    let number : Int
    // This type has a single initializer
    init() {
        number = 10
    }
}

let a = Foo.init // a's type: () -> Foo

So far so good. Now, let's add in a second initializer:

extension Foo {
    init(customNumber: Int) {
        number = customNumber
    }
}

Now, if you want to capture a reference to one of the initializers, you can
annotate the variable with the explicit function type:

let a : () -> Foo = Foo.init
let b : Int -> Foo = Foo.init

My question involves the case where you have multiple initializers that
take the same arguments and types. How would you capture initializers then?

extension Foo {
    init(numberToInc: Int) {
        number = numberToInc + 1
    }
}

How do I capture a reference to the numberToInc: initializer, versus the
customNumber: initializer?

Best regards,
Austin


(Pierre Monod-Broca) #2

Hi,

I had the same problem with delegate methods (they all had the same prefix). I used lambda as a workaround, but I agree it is less elegant :

let b: = { Foo(customNumber: $0) }
let c: = { Foo(numberToInc: $0) }

Pierre

···

Le 10 déc. 2015 à 23:41, Austin Zheng via swift-users <swift-users@swift.org> a écrit :

Hello Swift users,

I have a question about capturing references to initializers. You can do the following right now:

struct Foo {
    let number : Int
    // This type has a single initializer
    init() {
        number = 10
    }
}

let a = Foo.init // a's type: () -> Foo

So far so good. Now, let's add in a second initializer:

extension Foo {
    init(customNumber: Int) {
        number = customNumber
    }
}

Now, if you want to capture a reference to one of the initializers, you can annotate the variable with the explicit function type:

let a : () -> Foo = Foo.init
let b : Int -> Foo = Foo.init

My question involves the case where you have multiple initializers that take the same arguments and types. How would you capture initializers then?

extension Foo {
    init(numberToInc: Int) {
        number = numberToInc + 1
    }
}

How do I capture a reference to the numberToInc: initializer, versus the customNumber: initializer?

Best regards,
Austin
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