I dunno... it doesn't seem to satisfy this check, even though the article you sent me states maps are pointers (but does satisfy == reflect.Map). Doesn't the unmarshaller check for a pointer using == reflect.Ptr before it does anything? I haven't looked at it lately (can't atm, so going on memory)... but I think it does.
https://play.golang.org/p/lX7P2FtRlMo On Tuesday, January 30, 2018 at 9:29:09 AM UTC-6, Trig wrote: > > I guess it's not needed. I know that the json unmarshaller requires a > pointer to a struct... so for consistency, I was just stating it as a > pointer. I had no idea that make(map) returns *hmap. > > On Tuesday, January 30, 2018 at 9:13:28 AM UTC-6, matthe...@gmail.com > wrote: >> >> Dave talks about map representation here: >> https://dave.cheney.net/2017/04/30/if-a-map-isnt-a-reference-variable-what-is-it >> >> I don’t understand why you need a pointer to a map, can you provide a >> code example? >> >> Matt >> >> On Tuesday, January 30, 2018 at 8:22:54 AM UTC-6, Trig wrote: >>> >>> Appreciate the response. I'm wanting to pass a *map[string]interface{} >>> where the keys (strings) are already populated. I'm thinking of just >>> creating a func which does this itself... checks to see if the keys exists >>> and populate accordingly, and if not... return an error. Don't think this >>> will be too difficult; however, would be a nice feature to discuss about >>> being implemented into the json standard library. >>> >>> On Tuesday, January 30, 2018 at 5:31:01 AM UTC-6, Konstantin Khomoutov >>> wrote: >>>> >>>> On Sun, Jan 28, 2018 at 10:59:58AM -0800, Trig wrote: >>>> >>>> > This works as intended when you pass it a pointer to a Struct; >>>> however, it >>>> > should also work (you would think, since the Unmarshaller can handle >>>> both >>>> > types) a pointer to a *map[string]interface{}; however, it does not. >>>> Are >>>> > there any future plans to implement this option on both types? >>>> >>>> You're talking about [1], are you? >>>> >>>> If yes, the commit [2] which closed it specifically talks about struct >>>> types, so the function behaves as documented. >>>> >>>> On the other hand, I have two questions to narrow the scope of your >>>> claim down. >>>> >>>> - To carry out its intended task, DisallowUnknownFields() has to >>>> operate >>>> on a value which it can use to figure out the set of known fields. >>>> >>>> In the case of a map this suggests that the map passed to that >>>> method >>>> must be populated with the keys which would define the names of >>>> the known fields (and the values assigned to those keys are expected >>>> to be overwritten by the decoding process). Is this what you're >>>> proposing? >>>> >>>> - Why a pointer to a map? >>>> >>>> In my eyes, this suggests that you may legitimately pass a pointer >>>> to an unitialized map value and expect the decoder to create one for >>>> you; is that correct? >>>> >>>> If "yes" is the answer to the both points, they cannot be satisfied >>>> together: to fulfill the first requirement the map value must be >>>> non-nil, >>>> and you cannot expect the decoder to initialize it for you. >>>> >>>> All in all, I suggest you to create a proposal in the issue tracker. >>>> Just be sure to be crystal clear, when laying it out -- to save the >>>> devs >>>> from guessing what you really meant. >>>> >>>> 1. https://github.com/golang/go/issues/15314 >>>> 2. >>>> https://github.com/golang/go/commit/2596a0c075aeddec571cd658f748ac7a712a2b69 >>>> >>>> >>>> -- 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.
