This is https://github.com/golang/go/issues/48522 which is described in the
original proposal document but was deemed inessential for the
implementation in 1.18. This will likely come in a later release.
On Monday, February 21, 2022 at 7:13:24 AM UTC-5 Brian Candler wrote:
> Just to add an observation, it also doesn't work if you embed the struct:
>
> type A struct {
> x int
> }
>
> type B struct {
> A
> }
>
> ...even though in non-generic code m.x would be valid if m is of type B.
>
> On Monday, 21 February 2022 at 10:41:35 UTC Yulrizka wrote:
>
>> Hi All,
>>
>> I'm just trying generics and bump into this.
>>
>> # command-line-arguments
>> ./main.go:21:12: m.x undefined (type T has no field or method x)
>>
>>
>> this is the source code
>> package main
>>
>> import "fmt"
>>
>> type A struct {
>> x int
>> }
>>
>> type B struct {
>> x int
>> y int
>> }
>>
>> type Model interface {
>> A | B
>> }
>>
>> func Reduce[T Model](arr []T) int {
>> sum := 0
>> for _, m := range arr {
>> sum += m.x
>> }
>>
>> return sum
>> }
>>
>> func main() {
>> a := []A{
>> {x: 1},
>> {x: 2},
>> }
>> v := Reduce[A](a)
>> fmt.Printf("v = %+v\n", v)
>> }
>>
>> It does work however if I take out (`y int`) out of B struct. meaning A &
>> B has the same properties
>>
>> I can imagine that this is very trivial example and can be solve not by
>> using generic ( eg. with method dispatch by providing getter of X)
>>
>> I'm trying to clean up existing source code using generics in similar
>> situation. It's an ETL process with model that has a lot of attribute. Not
>> looking forward to adding extra method on the struct.
>>
>> Is there a better approach? I wonder why this is not supported currently.
>>
>> Thanks
>>
>
--
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/5bfae092-64bf-4e24-84ce-ba79165c4c51n%40googlegroups.com.
