Regardless, that's the reason what you've attempted doesn't work. It has its own entry in the Go FAQ: https://go.dev/doc/faq#covariant_types
On Wednesday, March 13, 2024 at 1:00:34 PM UTC-4 Rodrigo Araujo wrote: > 'Cause this dependency makes code more "rigid". A refactor in an isolated > package would let to change other packages. Also makes testing more > difficult. > It is kind of described here: > https://go.dev/wiki/CodeReviewComments#interfaces > > Em qua., 13 de mar. de 2024 às 13:41, burak serdar <bse...@computer.org> > escreveu: > >> On Wed, Mar 13, 2024 at 10:31 AM Rodrigo Araujo <yol...@gmail.com> wrote: >> > >> > Do you mean b.GetChilder? In this case, package A will depend on >> package B and I don't think this is a good approach. >> >> Why would it not be a good approach? You have a package declaring >> interfaces, and if you have another package using those interfaces, >> you import the first package in the second. Placing common interfaces >> in a package everyone else imports is a common way to deal with this >> problem. >> >> >> > >> > Em qua., 13 de mar. de 2024 às 11:28, Brian Hatfield < >> bmhat...@gmail.com> escreveu: >> >> >> >> Client.GetChild() must return GetChilder, not Child. >> >> >> >> On Wed, Mar 13, 2024 at 10:02 AM Rodrigo Araujo <yol...@gmail.com> >> wrote: >> >>> >> >>> Given the code bellow, I'm trying to keep my packages completely >> separated, without knowing each other, but the code doesn't work. I just >> can get it running when I define (or use) an interface from one package >> inside code of the other package. >> >>> Here is the error: >> >>> cannot use client (variable of type *a.Client) as b.GetChilder value >> in struct literal: *a.Client does not implement b.GetChilder (wrong type >> for method GetChild) >> >>> have GetChild() *a.Child >> >>> want GetChild() b.GetDataercompilerInvalidIfaceAssign >> >>> >> >>> package a // file: a/a.go >> >>> >> >>> import "fmt" >> >>> >> >>> type Client struct{} >> >>> >> >>> func (c *Client) GetChild() *Child { >> >>> return &Child{} >> >>> } >> >>> >> >>> type Child struct{} >> >>> >> >>> func (c *Child) GetData() { >> >>> fmt.Println("from GetData") >> >>> } >> >>> >> >>> >> >>> package b // file: b/b.go >> >>> >> >>> type GetDataer interface { >> >>> GetData() >> >>> } >> >>> >> >>> type GetChilder interface { >> >>> GetChild() GetDataer >> >>> } >> >>> >> >>> type Processor struct { >> >>> Client GetChilder >> >>> } >> >>> >> >>> func (p *Processor) Process() { >> >>> card := p.Client.GetChild() >> >>> card.GetData() >> >>> } >> >>> >> >>> >> >>> package main // file: main.go >> >>> >> >>> import ( >> >>> "interfaces/a" >> >>> "interfaces/b" >> >>> ) >> >>> >> >>> func main() { >> >>> client := &a.Client{} >> >>> processor := &b.Processor{ >> >>> Client: client, >> >>> } >> >>> processor.Process() >> >>> } >> >>> >> >>> >> >>> Why this doens't work? Some kind of limitation on interfaces usage? >> >>> How is the best approach (idiomatic golang) to tacke this kind of >> problem? >> >>> >> >>> >> >>> -- >> >>> 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/41be202c-f205-4adf-aecc-0f8e681e2490n%40googlegroups.com >> . >> > >> > >> > >> > -- >> > Att. >> > ---------------------- >> > Rodrigo Araujo >> > ---------------------- >> > >> > -- >> > 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/CAEwyvWHKZboz2KQvU7o_yneYhY31r3HBxqSQJw-B-vkuRvxHXw%40mail.gmail.com >> . >> >> -- >> > You received this message because you are subscribed to a topic in the >> Google Groups "golang-nuts" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/golang-nuts/E9EwsXSKg74/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> golang-nuts...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/CAMV2Rqr6PmqU%2BHNaNwW8fOZrv6SZw7cf2pacoR_tzvd3hd0MDA%40mail.gmail.com >> . >> > > > -- > Att. > ---------------------- > Rodrigo Araujo > ---------------------- > -- 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/23f6d878-2f82-4d4b-8ea1-350e3cfe7d13n%40googlegroups.com.
