On Sun, Jul 12, 2020 at 9:33 PM Bakul Shah <ba...@iitbombay.org> wrote:
> On Jul 12, 2020, at 11:11 AM, Gert <gert.cuyk...@gmail.com> wrote: > > > > https://play.golang.org/p/6xMgjr1IyFD > > > > var fn myHandler > > fn = func(w http.ResponseWriter, r *http.Request) { > > fn.GET(w, r) > > } > > > > Just wondering if it's possible somehow to write this in one line like so > > > > var fn myHandler = func(w http.ResponseWriter, r *http.Request) { > > fn.GET(w, r) > > } > > The issue is that fn's type can't be completely determined until > the RHS func is fully analyzed but for that to work fn must be > known! Why? ISTM the type is mentioned twice - once as "myHandler" on the LHS and once in the signature on the RHS. And there isn't even a way to write down a function literal without mentioning the full type. On the surface, this seems like a relatively straightforward scoping issue, introduced by the fact that the scope of a variable declaration starts at the end of it's VarSpec, not the "=". Interestingly though, the initialization rules prevent this from working at the package-level, where this scoping problem doesn't exist: https://play.golang.org/p/IPMxtYETGsg Also note that the first definition won't do what you may be thinking > it does. The`fn.GET` call will be to the existing value of fn, not > the result of the assignment. > No, it won't. The function-literal closes over `fn`, so it will use whatever is assigned at call-time. https://play.golang.org/p/VCvCt8J8Zcw I use this pattern all the time to define a recursive function without polluting the package-scope. > -- > 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/716C7D59-9F2B-4AAD-8560-79011359A96C%40iitbombay.org > . > -- 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/CAEkBMfHyQUYAajYFPomomo-SOn2t_gY%3DntJFcs4Sn4qfVFXUxA%40mail.gmail.com.
