On Thursday, September 29, 2016 at 1:07:42 PM UTC+8, Henrik Johansson wrote: > > I am not sure but perhaps as simple as it is a very natural and known > behavior of maps and to make it work syntactically as the type assertion > would make it weird. > > yes. It is really weird that the behavior of type assertion depends on whether the second OK result value is received or not.
> On Thu, Sep 29, 2016, 07:02 T L <tapi...@gmail.com <javascript:>> wrote: > >> >> >> On Thursday, September 29, 2016 at 12:56:57 PM UTC+8, Micky wrote: >>> >>> The reason is directly stated in the Go language spec: >>> >>> "If the type assertion holds, the value of the expression is the value >>> stored in x and its type is T. If the type assertion is false, a run-time >>> panic <https://golang.org/ref/spec#Run_time_panics> occurs." >>> >>> Here "hold" means if it succeeds. >>> >>> >> I know of the syntax in spec. >> I just want to understand what is the deep reason for the syntax >> inconsistency between map index and type assert. >> >> >>> >>> On Thu, Sep 29, 2016 at 9:53 AM, T L <tapi...@gmail.com> wrote: >>> >>>> >>>> >>>> On Thursday, September 29, 2016 at 12:32:48 PM UTC+8, Henrik Johansson >>>> wrote: >>>>> >>>>> This is just how type assertion works. >>>>> If you don't use the dual return it panics if the actual type is >>>>> different from the one you try to assert. >>>>> >>>> >>>> but what is the underlining reason for the inconsistency between map >>>> index and type assert? >>>> >>>> >>>>> >>>>> On Thu, Sep 29, 2016, 05:26 T L <tapi...@gmail.com> wrote: >>>>> >>>>>> package main >>>>>> >>>>>> func main() { >>>>>> var m = map[string]int{} >>>>>> _, _ = m["abc"] // ok >>>>>> _ = m["abc"] // ok >>>>>> >>>>>> var i interface{} = 789 >>>>>> _, _ = i.(bool) // ok >>>>>> _ = i.(bool) // panic: interface conversion: interface is int, >>>>>> not bool >>>>>> } >>>>>> >>>>>> -- >>>>>> 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. >>>>>> 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...@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...@googlegroups.com <javascript:>. >> 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.
