I'd note the following: https://play.golang.org/p/U_lmt-go6M
Also, this can be simplified to the following: https://play.golang.org/p/eFnM98yRLk Such a puzzle should look something more like: https://play.golang.org/p/8KD6INL9QP On Sun, Nov 19, 2017 at 6:25 PM Carl Mastrangelo <carl.mastrang...@gmail.com> wrote: > Hi gophers, > > I was playing around with a puzzle trying to break the sync package and > found something cool. Can you think of a definition for f that causes > once.Do to execute the argument more than once? > > > package main > > import ( > "sync" > ) > > func main() { > var once sync.Once > var f = // ... > > once.Do(f) > } > > > HIGHLIGHT BELOW FOR ANSWER > > > package main > > import ( > "fmt" > "sync" > ) > > func main() { > var once sync.Once > var f func() > times := 9 > f = func() { > if times == 0 { > return > } > times-- > fmt.Println("Called") > oldonce := once > *&once = sync.Once{} > once.Do(f) > once = oldonce > > } > once.Do(f) > } > > HIGHLIGHT ABOVE FOR ANSWER > > -- > 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. > -- 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.
