If I understand you correctly, you are suggesting to replace the parameter type `func(http.ResponseWriter, *http.Request)` with the parameter type `http.HandlerFunc`. You've been (correctly) told that we can't make that change, because it would break the Go 1 compatibility change (as there is code which currently compiles which wouldn't compile after that change). But you are wondering if, *ignoring* the compatibility guarantee, it would be a good change. Am I getting this right?
If so: I don't think it would be a good change. First, it's important to realize that the *only* reason, `http.HandlerFunc` exists at all, is so that you can write a `func(http.ResponseWriter, *http.Request)` and use it as a `http.Handler`, in the places where `net/http` expects the latter. You say the type isn't used - but it is. It's used by *users* of the `net/http` package, to make their plain functions into `http.Handler`s. It is also used in `net/http` itself - in the exact function you are referring to <https://golang.org/src/net/http/server.go?s=77627:77714#L2487>. That is the exact and only purpose of that type, to make a plain function implement the `Handler` interface. So, taking a plain function as a parameter *is the purpose of having the `HandlerFunc` type*. You also say that adding types is a good thing. I tend to disagree with that as a general statement. Adding types is a good thing, if it serves as important documentation or if it serves to catch bugs. I don't think either of these would be happening with this change. In terms of documentation - well, you don't *have* to pass a `http.HandlerFunc`, so there is no reason for the documentation to make it clear that you should. You can (and should) just pass a plain `func`. So, using the defined type here wouldn't serve as documentation, it would document the *wrong* thing. As for catching bugs: Making the parameter type a defined type would only change one thing in terms of type-safety. It would mean that if you define a *different* type `type MyFunc func(http.ResponseWriter, *http.Request)`, the compiler would prevent you from writing `http.HandleFunc(…, MyFunc(f))`. Preventing a bug would thus require that your `MyFunc` type would have to be used semantically differently from `http.HandlerFunc`. But that seems *exceedingly* unlikely, given that you defined `MyFunc` in terms of the `net/http` package. And it would then appear *exceedingly* unlikely, that you'd accidentally mix the two up - almost all usages of `http.HandleFunc` will pass the name of some defined function and that will always work. But all of this discussion is really moot. It's a breaking change, so it can't happen - whether it's a good change or not doesn't exactly matter at that point. Personally, *if* we could "go back in time" and wouldn't have to worry about backwards compatibility, my vote would rather be to change the language to make the HandlerFunc type obsolete <https://github.com/golang/go/issues/21670> and remove it altogether. On Sun, Jun 27, 2021 at 3:53 PM Victor Giordano <vitucho3...@gmail.com> wrote: > Hello gophers! > > While studing at this source code > <https://github.com/golang/go/blob/37f9a8f69d6299783eac8848d87e27eb563500ac/src/net/http/server.go> > in search for some knowledge and enlightment, i do note that in some file a > type is defined and then is not used in a place where it could be used. > This open an interrogant for me, because tipification is often good thing, > regardless the language I may state, and I express it via a ticket > <https://github.com/golang/go/issues/46926>. I get the idea that due to > language grammar changing the code would be a breaking change. > > But i keep wondering if they actually do this for a reason.. i mean, given > the possiblity to get back in time, ¿does the team at golang will write the > same source code, definiting a type with a name and then intenttionally not > using it? i mean...i keep wondering if there is any reason for defined > types and then not use it and using the gitlab channel i probably fail to > express my initial intention. I do often read some third party code, in > order to view others minds (or try at least..), what i'm asking here is a > question in order to get another people point of view. > > Thanks again! > > -- > 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/96369719-6200-4765-aee1-83befce04666n%40googlegroups.com > <https://groups.google.com/d/msgid/golang-nuts/96369719-6200-4765-aee1-83befce04666n%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/CAEkBMfHnCTf_4G5ZhGX0EXBKJRN9LcEWbKWOdPiCTKdX6SDqPA%40mail.gmail.com.
