Hopefully by the title of this, it's clear I'm not asking does Swift support the Switch statement. I'm specifically asking if Swift supports Switch expressions, akin to what C# has.
The difference is subtle, but important. A Switch statement is a way to group lines of code based on a particular case. A Switch expression however returns a value based on a particular case.
Say you have the following enum...
enum SomeEnum {
case a
case b
case c
}
Now say you need to calculate/return some value based on the particular switch statement. Currently, in Swift you have to use a Switch statement to do this...
let someEnumValue: SomeEnum = .a
let result: String
switch someEnumValue {
case .binary: result = "This is the 'A' type"
case .octal: result = "This is the 'B' type"
case .hexadecimal: result = "This is the 'C' type"
}
print(result)
//prints 'This is the 'A' type'
As you see above, in Swift, you have to first declare let result: String but not give it a value, then within the Switch statement, you have to assign the value there. This is because a Switch statement doesn't return a value. It only executes code based on the matching case/condition. (Yes, you could also put all that in a function and simply call that, but that's separate from this question.)
C# Switch Expression
In contrast, here's how you would write it in C# with a Switch expression...
var result = someEnum switch {
SomeEnum.a => "This is the 'A' type",
SomeEnum.b => "This is the 'B' type",
SomeEnum.c => "This is the 'C' type"
}
Console.WriteLine(result)
//prints 'This is the 'A' type'
As you can see here, the Switch expression directly assigned a value to the result variable since a Switch expression returns a value.
Of note: Unlike with a Switch statement where the word 'switch' goes before the variable, in a Switch expression, the word switch goes after the variable. Additionally, within the braces, the individual cases are separated by commas. Finally, every case can only be a single expression that produces a value. You can't run compound statements unless you first wrap them in their own function.
Pseudo version with Closures
A colleague of mine came up with this approach which uses an in-place closure. It's a little better, but still not quite as simple as a true Switch expression...
let result = {
switch someEnum {
case .a: return "This is the 'A' type"
case .b: return "This is the 'B' type"
case .c: return "This is the 'C' type"
}
}()
print(result)
So my question is simple... does Swift support Switch expressions? If not, let's all suggest it to Swift.org because it makes things so much easier/simpler!