There's loads of precedence in the stdlib: https://godoc.org/net/http/#FileSystem.Open https://godoc.org/net/http#File.Stat https://godoc.org/net#Conn.LocalAddr https://godoc.org/database/sql/driver/#Driver.Open https://godoc.org/image#Image.ColorModel https://godoc.org/reflect/#Type.Elem And don't forget that error itself is an interface.
Honestly, if you need it, go for it. There are definitely places where it's over abstraction to do it, but I don't think there's a good or universal rule you can use to decide which is which. FWIW, I tend to disagree with the "return structs, accept interfaces" advise in general. If go had variant func/methods <https://golang.org/doc/faq#covariant_types>, that would be useful guidance. But as it stands, it is too often necessary to violate it (every usage of an error return value is in fact such a violation). And the "accept interfaces" part tends to lead to over abstraction (I would probably agree with "consider accepting interfaces if they already exist" though). On Wed, Oct 9, 2019 at 9:39 AM Martin Palma <m...@palma.bz> wrote: > I'm wondering If it is ok (or good Go code) if an interface method returns > an other interface? Here an example: > > type Querier interface { > Query() string > } > > type Decoder interface { > DecodeAndValidate() Querier > } > > > -- > 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/531f29a6-ea2e-4416-a0d0-ce697dc7a09b%40googlegroups.com > <https://groups.google.com/d/msgid/golang-nuts/531f29a6-ea2e-4416-a0d0-ce697dc7a09b%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/CAEkBMfHHtn5t3TZOCG4xA_3kVbNqY2_xo7EtHoLyhi6P28ku9g%40mail.gmail.com.
