> My use case is that I want to pretty print in-memory objects for debug purposes during testing, and one of the features would be to point out such cycles as this.
Consider using an existing library for this, for example: https://github.com/sanity-io/litter https://github.com/davecgh/go-spew On Wednesday, November 11, 2020 at 1:59:18 PM UTC+1 arpad....@gmail.com wrote: > `l[0] = l` would be fine for me, indeed. Though I am not sure I understand > the suggested solution. Notice that the type of the slice is > `[]interface{}`. This... > > ll := l[0].([]interface{}) > println(&l == &ll) > > ...would print `false`. > > I think the main challenge is that l and ll, or l[0] for that matter, are > not the same values. I tried with reflection, too, but couldn't figure a > way. > > PS: I am quite aware how unearthy this problem is, and how it should not > ever happen in case of actual programs. My use case is that I want to > pretty print in-memory objects for debug purposes during testing, and one > of the features would be to point out such cycles as this. > > > On Wednesday, November 11, 2020 at 8:13:55 AM UTC+1 > axel.wa...@googlemail.com wrote: > >> The question was about detecting cyclic references. For that, the `l[0] = >> l` case is enough. >> >> On Wed, Nov 11, 2020 at 2:31 AM jake...@gmail.com <jake...@gmail.com> >> wrote: >> >>> FYI, that does detect the simple case of l[0] = l, but not more >>> complicated circular cases like l[1] = l[1:] >>> >>> On Tuesday, November 10, 2020 at 2:38:26 AM UTC-5 >>> axel.wa...@googlemail.com wrote: >>> >>>> If the slice is empty, it doesn't reference anything. >>>> If it is not empty, &x[0] can be used to identify the slice >>>> (potentially also using len/cap, if it's interesting). >>>> >>>> On Tue, Nov 10, 2020 at 4:11 AM arpad ryszka <arpad....@gmail.com> >>>> wrote: >>>> >>>>> Hi, >>>>> >>>>> is there a way to detect the cyclic reference in the following example >>>>> somehow? Either via reflection or by other means? My understanding is >>>>> that >>>>> slices cannot be compared with == (unless to nil), or used as keys in >>>>> maps. >>>>> Is there a different way? >>>>> >>>>> l := []interface{}{"foo"} >>>>> l[0] = l >>>>> fmt.Println(l) >>>>> >>>>> or here it is as a playground link: >>>>> https://play.golang.org/p/T0qZlF8m-vi >>>>> >>>>> Cheers, >>>>> Arpad >>>>> >>>>> -- >>>>> 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/b2cb6b5e-febc-407f-b5b3-d9ca196ce68bn%40googlegroups.com >>>>> >>>>> <https://groups.google.com/d/msgid/golang-nuts/b2cb6b5e-febc-407f-b5b3-d9ca196ce68bn%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- >>> 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/250107e9-f688-4205-ae52-728221eb2e4cn%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/golang-nuts/250107e9-f688-4205-ae52-728221eb2e4cn%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- 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/cc25d4f0-51fa-4851-989b-fab4527bc709n%40googlegroups.com.
