> You can always solve name spacing issues by splitting it up into separate packages.
Or type aliases: https://go.dev/play/p/Slhgs8SLyo6 On Thursday, 15 June 2023 at 09:47:39 UTC+1 Axel Wagner wrote: > Type declarations in functions are only scoped from the point of their > declaration until the end of the function. > So the reason you can not do the recursive type definition in a function > is that at the point of the first declaration, the second is not yet in > scope. > Package scoped declarations are different from function scoped > definitions, because in a function, you have a notion of "progress" - one > statement comes after the next. At the package scope, that isn't he case. > All package scoped declarations are "simultaneous", in a sense. That was > intentional, to avoid an issue C has, where you have to sometimes declare a > function before separately, to get mutual recursion. > > I think it would have been possible to make type declarations apply to the > entire function scope. But that wouldn't even solve the entire issue - for > example, you run into a similar problem when defining recursive functions > locally. Python does actually solve this by making every declaration apply > to the entire function scope - but that has its own surprises. Either way, > it's a decision that was made and we can't really reverse it now, as it > would break existing code. For example, you can do this today: > > func F(x int) { > x = 42 > type x string > var y x > } > > which would presumably break. > > Ultimately, you just have to bite the bullet here and define your types at > package scope. You can always solve name spacing issues by splitting it up > into separate packages. > > On Thu, Jun 15, 2023 at 10:32 AM Christophe Meessen < > christoph...@gmail.com> wrote: > >> The following playground example shows the problem: >> >> https://go.dev/play/p/1kC2j57M_fW >> >> >> Le 15/06/2023 à 10:28, Jan Mercl a écrit : >> > On Thu, Jun 15, 2023 at 10:16 AM christoph...@gmail.com >> > <christoph...@gmail.com> wrote: >> > >> >> It is possible to define two structures globally with mutual type >> dependency as this: >> >> >> >> type A struct { >> >> B []B >> >> } >> >> >> >> type B struct { >> >> A A[] >> >> } >> >> >> >> but I just noticed that we can't do that inside a function: >> >> >> >> func Foo() { >> >> type A struct { >> >> B []B >> >> } >> >> >> >> type B struct { >> >> A A[] >> >> } >> >> } >> >> >> >> Is there a reason for this limitation ? >> > Syntax error: https://go.dev/play/p/ZOGyZyQDW0I >> >> -- >> Bien cordialement, >> Ch.Meessen >> >> -- >> 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...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/801e7e6b-d3f8-c1df-8eae-46aa619d49a5%40gmail.com >> . >> > -- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/38adb9bf-ddc7-49e0-bad2-1a72b3a8c849n%40googlegroups.com.
