Multiple return type or callback function

[pineapple via Digitalmars-d-learn]

On Monday, 23 January 2017 at 15:15:35 UTC, aberba wrote:
> I'm creating a function to authenticate user login. I want to 
> determine login failure (Boolean) and error message (will be 
> sent to frontend) but D does have multiple return type (IMO 
> could use struct but will make code dirty with too much custom 
> types).
>
> struct Result
> {
>     bool success = false
>     string message;
> }
> Result authen(){}
> auto r = authen()
> if (r.success) writeln(r.message);

I use structs like this quite frequently, myself. It works well 
and I don't think it's particularly ugly. And if you don't want 
to pollute the namespace with one-off structs, you can also place 
them inside the function that's returning them (making them 
voledmort types).