Static var being treated as let constant?

Question

I have a struct (someUrl) containing 3 static vars:

struct someUrl {
    static var keywords = String()
    static var someUrlStart = String()
    static var someUrlEnd = String()
}

and a class (Url) with a variable of type someUrl:

class Url {
    var someUrlConstructor: someUrl

    init(keywords: String, someUrlEnd: String, someUrlStart: String) {
        self.someUrlConstructor = someUrl(someUrlStart = someUrlStart, keywords = keywords, someUrlEnd = someUrlEnd)
    }

}

In trying to initialize the variable in the class, Xcode is throwing an error stating that someUrlStart is a let constant.

cannot assign to value: 'someUrlStart' is a 'let' constant

This is ALL I have in my code so far, and I don't get why a static var would be treated as a constant. Is this specific to initializers?

Answer 1

You are confusing the compiler here. First your syntax is wrong in terms of how you pass parameters, it should be : instead of =, then you should remove the static and change the order of the parameters:

struct someUrl {
    var keywords = String()
    var someUrlStart = String()
    var someUrlEnd = String()
}

class Url {
    var someUrlConstructor: someUrl

    init(keywords: String, someUrlEnd: String, someUrlStart: String) {
        self.someUrlConstructor = someUrl(keywords: keywords, someUrlStart: someUrlStart, someUrlEnd: someUrlEnd)
    }
}

Alternatively if you want to keep them static remove the parameters completely since now they are static variables and not member / instance variables:

struct someUrl {
    static var keywords = String()
    static var someUrlStart = String()
    static var someUrlEnd = String()
}

class Url {
    var someUrlConstructor: someUrl

    init(keywords: String, someUrlEnd: String, someUrlStart: String) {
        self.someUrlConstructor = someUrl()
    }
}

What the compiler thought you were doing (or basically what you were in fact doing writing =) was trying to change the someUrlEnd (and the other two) you were given as a initializer parameter which is in fact a constant.

---

Apart from the wrong syntax I do not see a use for the static or for the class Url, just take the struct someUrl, its default initializer and go from there. General note: please upper case the first letter of the struct: SomeUrl.