On Wed, Aug 2, 2017 at 6:30 AM, Mandolyte <cecil....@gmail.com> wrote: > This line of code: > retrTarget := path.Join(maindir, ss[0], pathparts[npp:]...) > > produces this error: > .\xxx.go:131: too many arguments in call to path.Join > have (string, string, []string...) > want (...string) > > Easy to work around, but I don't understand why it doesn't work...
The declaration of path.Join is `Join(elem ...string) string`. When a function has a `...string` parameter, you can either pass a sequence of strings, or you can pass a slice as `s...`. If you pass a slice, the slice is passed directly as an ordinary slice parameter: if the function changes any elements, those changes will be reflected in the caller's slice. If you just pass a sequence of strings, a new slice is constructed and the caller will not see any changes. Because of this difference in behavior, the language does not support passing both a sequence of arguments and a slice, as that would make it harder to understand when a slice is passed by reference and when a new slice is constructed. Also, the language generally avoids constructs that look simple but do not take linear time Passing a sequence of strings takes time (and space) proportional to the number of arguments. Passing a slice takes constant time. Passing a sequence of string plus a slice would require creating a new slice to hold all the arguments, and as such would take time proportional to the number of string arguments plus the size of the slice, which is only known at run time. In other words, a simple seeming language construct would require an unpredictable amount of run time. The language avoids such cases in general, other than cases like the predeclared copy and append functions where the unpredictable time is fairly obvious. Ian -- 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.
