FWIW, arguing that `http.HandleFunc` should take a `http.HandlerFunc` because there exists a defined type with the same underlying type as the parameter is a bit like arguing every function that takes an `int64` should instead take a time.Duration <https://golang.org/pkg/time/#Duration>. That's just not how types tend to work.
It makes no sense for `http.HandleFunc` to take a `http.HandlerFunc`, because it's purpose is specifically to work on a plain function. If you have an `http.HandlerFunc`, you can already just call `http.Handle` - there is no need to make a separate function that takes a *specific* implementation of `http.Handler`. On Sun, Jun 27, 2021 at 5:51 PM Axel Wagner <axel.wagner...@googlemail.com> wrote: > On Sun, Jun 27, 2021 at 5:25 PM Victor Giordano <vitucho3...@gmail.com> > wrote: > >> I keep wondering if they code that way for any reason. With "code that >> way" I mean: define a type and then not use it. >> > > As I said: It's used plenty of times. Both inside of `net/http` and > outside of it. > >> >> - So, ¿why not employ the type defined in the first place? >> >> I feel like I gave a bunch of reasons for this too. > > >> Don't get me wrong,but if I define a type I tend to use that type where >> it appears. That is in fact the basis of making types, to use them. So that >> feeds my questioning! >> >> >> El dom, 27 jun 2021 a las 11:46, 'Axel Wagner' via golang-nuts (< >> golang-nuts@googlegroups.com>) escribió: >> >>> 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 a topic in the >>> Google Groups "golang-nuts" group. >>> To unsubscribe from this topic, visit >>> https://groups.google.com/d/topic/golang-nuts/VBQrlI6-zW0/unsubscribe. >>> To unsubscribe from this group and all its topics, 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 >>> <https://groups.google.com/d/msgid/golang-nuts/CAEkBMfHnCTf_4G5ZhGX0EXBKJRN9LcEWbKWOdPiCTKdX6SDqPA%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> >> >> -- >> V >> > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. 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