[swift-evolution] Automatic generation of initializer including default values

[Robert Widmann]

I'm ambivalent here.  I know this is convenient, but I have a stronger interest in controlling my APIs, initializers included.  The more the compiler synthesizes, the less control I have and the more code I have to write to make up for that.  I don't think there's enough here (yet?) to justify synthesis.

tl;dr  Not everybody chains convenience initializers like this.

~Robert Widmann

2016/10/10 8:27、Guy Miller via swift-evolution <swift-evolution at swift.org> のメッセージ:

> Hi,
> 
> When I am defining a struct I find myself often using a style as shown in the following example:
> 
> struct Foo {
> 
>    var greeting: String
>    var x: Int
>    var y: Int
>    var z: Int
> 
>    init(greeting: String, x: Int = 1, y: Int = 2, z: Int = 3) {
>        self.greeting = greeting
>        self.x = x
>        self.y = y
>        self.z = z
>    }
> }
> 
> This enables one to write code when one doesn’t need to change defaults:
> 
> let f = Foo(greeting: “Hello”)
> 
> and when one wishes to change one of the defaults:
> 
> let f = Foo(greeting: “Hello”, z: 4)
> 
> It would be better if one could write the struct in what I understand is the preferred style:
> 
> struct Foo {
>    var greeting: String
>    var x = 1
>    var y = 2
>    var z = 3
> }
> 
> and have the compiler generate the initializer:
> 
> init(name: String, x: Int = 1, y: Int = 2, z: Int = 3) {
>    self.name = name
>    self.x = x
>    self.y = y
>    self.z = z
> }
> 
> rather than one where all the parameters that have a default value need to be specified in the initializer if one wishes to change just one of them.
> 
> Regards,
> Guy Miller
> 
> 
> 
> 
> _______________________________________________
> swift-evolution mailing list
> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution