Extract self-properties in block-method

Question

I have some trouble in understanding my specific request, in Swift. There is a class named Origin and multiple its subclasses. How I can update my block-method written ONLY in Origin class?

class Origin: NSObject {
    func mod(_ block: (() throws -> Void)) {
        try! block()
    } 
}

I need use mod from all Origin subclasses, and I need to have this usage effect:

var originSubclassObject = OriginSubclass() 
originSubclassObject.mod {
    .age = 12 //age is OriginSubclass property
    .name = "Bob" //name is OriginSubclass property
}

So, you see, I need extract OriginSubclass properties for using in mod-block. I need to create usage exactly likes in usage effect code (extract mod-caller properties from "."). Thanks all for help!

Compare https://stackoverflow.com/a/42356615/2976878 – Hamish Sep 23 '17 at 22:49 — Hamish, Sep 23 '17 at 22:49

Rob · Accepted Answer · 2017-09-23T23:00:22.103

You could consider a protocol with a default implementation, e.g.:

protocol Modifiable { }

extension Modifiable {
    func mod(_ block: ((Self) throws -> Void)) {
        try! block(self)
    }
}

class Origin: Modifiable { }

class OriginSubclass: Origin {
    var name: String?
    var age: Int?
}

And then:

let originSubclassObject = OriginSubclass()
originSubclassObject.mod { object in
    object.age = 12
    object.name = "Bob"
}

Or

let originSubclassObject = OriginSubclass()
originSubclassObject.mod {
    $0.age = 12
    $0.name = "Bob"
}

Or, if that base class was only there for the mod method, you could lose it entirely:

protocol Modifiable { }

extension Modifiable {
    func mod(_ block: ((Self) throws -> Void)) {
        try! block(self)
    }
}

class MyObject: Modifiable {
    var name: String?
    var age: Int?
}

And

let myObject = MyObject()
myObject.mod { object in
    object.age = 12
    object.name = "Bob"
}

Or

let myObject = MyObject()
myObject.mod {
    $0.age = 12
    $0.name = "Bob"
}

Extract self-properties in block-method

1 Answers1