I have a lazy variable that is not initialised:
lazy var time: () -> String = {
return String(describing: Date())
}
Whenever I call time() I get a new Date. So it seems like it behaves exactly like:
var time: () -> String {
return {
return String(describing: Date())
}
}
In this context, is it bad practice just to use the lazy closure, because then I don't have to write two return-statements in a row or do I miss something?
You don't need two return statements in a row nor do you need a lazy closure. Why not just do:
let time: () -> String = {
return String(describing: Date())
}
Or just replace this whole thing with a method:
func time() -> String {
return String(describing: Date())
}
One reason why you might want to use a closure here is that you want other parts of your code to change the value of the closure. If that's the case, just do it like the first snippet, otherwise I don't think anything is preventing you from writing a method. You can pass a method around just like a closure, because methods are a kind of closure!
Lazy variables are really needed when initializing them takes much resources. Creating closures tend to be cheap.
lazy and it's bad practice to make it a property. It should be a function, as in the last example. It's bad practice to make it lazy because there's no reason to delay the initialization. (It's like writing lazy var x = 4; it's legal but pointless.) It shouldn't be a property because it doesn't act like a property. Despite nothing changing about the struct, the value is different every time it's called. This isn't "property-like."
Date to String using String(describing:) should only be used when debugging. Never do that for any other situation. Use a DateFormatter for all other cases. Use date/timeStyle if showing the date to a user. Use dateFormat if a fixed format is needed to send to a server, for example.
lazy var timeis initialized only once – to a closure that, when called, returns a string with the current date.func time() -> String { return String(describing: Date()) }?