On Friday, October 14, 2016 at 12:14:34 AM UTC+8, Ian Lance Taylor wrote: > > On Thu, Oct 13, 2016 at 8:36 AM, <di...@veryhaha.com <javascript:>> > wrote: > > > > On Thursday, October 13, 2016 at 11:24:50 PM UTC+8, Jesper Louis > Andersen > > wrote: > >> > >> The rule is that a short variable declaration requires that at least > one > >> non-blank variable is new (the specification even says so) Consider > >> > >> _, y := 4,5 > >> > >> where one variable, y, is new. In > >> > >> _ := 6 > >> > >> or > >> > >> _, _ := 5, 7 > >> > >> this rule is violated, since there are no non-blank variables (and thus > >> vacuously nothing new). > >> > >> I think the reason this is a rule is because it may detect some > spurious > >> errors by forcing the programmer to write code in a certain style, but > I may > >> be wrong. > > > > > > > > What spurious errors? > > The error of thinking that because you are using := you are getting a > new variable. > > The handling of := is a bit tricky, perhaps too tricky. It used to > always declare new variables, and give an error if there was already a > variable of the same name in the same scope. But that was too painful > to use with the err variable, because of the common use of > n, err := F() > So := was changed to permit reusing a variable if it already existed > in the same scope with the same name and (inferred) type. > > Ian >
But the long variable declaration form only allows all variables are new ones generally, except for the blank _ identifier. Why not also make an exception for the blank _ identifier in the short form? -- 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.
