To be honest, I always found this recommendation a little bit strange, personally.
I'll note that the standard library does not really keep to this either. For example, time.Time.UnmarshalText (obviously) has a pointer-receiver, while almost all other methods on time.Time have a value receiver. And if you implement flag.Value <https://pkg.go.dev/flag#Value>, the Set method obviously needs a pointer receiver, but if the String method has one as well, it won't print properly when used as a value <https://go.dev/play/p/2mezAoz85r6>. In basically every implementation of flag.Value I've ever written, String needed a value receiver, while Set needed a pointer receiver. I understand the basic idea of the advice, that if a type keeps state that is manipulated via methods, then it should generally be passed around as a pointer, so giving all the methods a pointer-receiver works well. But if a type *is* intended to be used as a value (like time.Time or Enum in my example) then you will almost certainly end up with a mix of receiver kinds - as soon as you want to add any form of de-serialization to it. So "don't mix receiver kinds" seems like misleading advice to me. On Mon, 7 Oct 2024 at 19:44, Ian Lance Taylor <i...@golang.org> wrote: > On Mon, Oct 7, 2024 at 10:29 AM Ken Lee <ken.lee.kiany...@gmail.com> > wrote: > > > > --- > > There is a consideration to make, though: historically it has been > considered bad form in Go to give a type a mix of value and pointer > receivers in methods without a very specific reason for doing so. > > --- > > > > Is this still the case now? As in 2024. > > As a general guideline, yes. > > https://go.dev/wiki/CodeReviewComments#receiver-type > > Ian > > > > > On Sunday 13 January 2013 at 7:03:29 am UTC+8 Kevin Gillette wrote: > >> > >> Indeed. In addition to implicit dereferencing for value receivers, the > reverse also works as well: anything that is addressable (including 'value' > variables on the stack, or a field of element of anything that's > addressable) will implicitly be addressed when a pointer-receiver method is > called on them (though you must explicitly use the address operator when > you need to pass value variables as pointers). > >> > >> There is a consideration to make, though: historically it has been > considered bad form in Go to give a type a mix of value and pointer > receivers in methods without a very specific reason for doing so. The > typical justification is that a small struct in a getter method might as > well have a value receiver even though the corresponding setter method uses > a pointer receiver; this, however, can lead to confusion on the part of the > app programmer if they start out using only the read-only methods upon what > turns out to be a value-copy of the original (but hey, it compiled and > seems to work, so it must be correct) -- when use of pointer-receiver > methods don't seem to produce the documented changes in the original, it > can be difficult to debug. > >> > >> > >> On Saturday, January 12, 2013 3:17:16 PM UTC-7, Dave Collins wrote: > >>> > >>> On Saturday, January 12, 2013 3:52:35 PM UTC-6, Taric Mirza wrote: > >>>> > >>>> Thanks! Works like a charm and is helping cleaning up my code a ton. > >>>> > >>>> One other question, this is really more about coding style: > >>>> > >>>> In the case where you manipulate members of the struct, then using > >>>> pointers as in your example is the way to go. > >>>> > >>>> But, you have a choice for functions that just read values from the > >>>> struct instead of manipulating it. Is there a best practice coding > >>>> style here, between dereferencing the struct and then using that, or > >>>> dereferencing each member of the struct as you go? eg: > >>>> > >>>> // A: > >>>> > >>>> laser := worldobj.(*Laser) > >>>> fmt.Printf("%0.4f,%0.4f", (*laser).x, (*laser).y) > >>>> > >>>> versus > >>>> > >>>> // B: > >>>> > >>>> laser := *(worldobj.(*Laser)) > >>>> fmt.Printf("%0.4f,%0.4f", laser.x, laser.y) > >>>> > >>>> > >>>> I'm kind of torn. I would imagine A) has slightly better > >>>> performance, and doesn't require any code-rework if you later on need > >>>> to manipulate the struct. > >>>> > >>>> On the other hand, B) is more readable since you don't have to look at > >>>> pointers all over the place, just on one line. > >>> > >>> > >>> Actually, you don't need to dereference at all. Go automatically > handles this for you. > >>> > >>> See this example: http://play.golang.org/p/ANaKaFSQLn > >>> > > -- > > 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/03df7dce-5c48-44a3-bc3c-851ded2a1f08n%40googlegroups.com > . > > -- > 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/CAOyqgcX7v9Edk5beRH38tfJO18ZUXv-nOHsEPPCfMQy0hz%3DFdw%40mail.gmail.com > . > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. 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