On Sunday, December 17, 2017 at 2:32:24 PM UTC-6, jlfo...@berkeley.edu wrote:
> > Here's something that someone new to Go might run up against. I know I did. > > Me, too! The trivial program below, derived from "The Go Programming Language" > book, shows two methods that differ only in the way they treat their > receiver. In the first, the receiver is a pointer to a slice, and in the > second, the receiver is a slice. So far so good. What confused me is > that both methods return the same result even when called the same way. > I would have expected only one of the methods to work. > > I never really figured out what was going on, but I finally just accepted it as "go is doing what I want it to do, even if I say it wrong." Here's what I believe is the explanation. The book says (slightly > edited) "If the receiver p is a variable of type Path but the method > requires a *Path receiver, we can use this shorthand: > > p.pr1() > > and the compiler will perform an implicit &p on the variable.". This > explains what happens when pr1() is called. > > Right. I guess this all works because there are so few things you can do with pointers; so this isn't going to create odd ambiguities. > I'm surprised that Go would include this implicit behavior because type > conversions are generally required to be explicit. > > I agree that it seems un-Go-like initially. But the more I think about it, the more it makes sense given other restrictions on pointers. The only thing you can do with pointers is pass them and deferences them. You never actually do anything with the value of the pointer itself. A type can have methods, but a pointer to a type can't. So it's always(?) going to be safe for the compiler to do this. Of course you don't want people using both forms within a local scope. So that is my guess at why the this "shortcut" is allowed only via receivers. I am, of course, speculating wildly. I would be pleased to be set straight by the people who actually know what is going on. And I pray to whatever is holy that I never take the habits I'm picking up with this back to C. -j -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
