I want to get member's reflect.Type via struct definition, but not it's instance.

[alswell]

What version of Go are you using (go version)?

$ go version
go version go1.10.4 linux/amd64

Does this issue reproduce with the latest release?

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/root/go"
GORACE=""
GOROOT="/usr/lib/go-1.10"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go-1.10/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build414398923=/tmp/go-build -gno-record-gcc-switches"

What did you do?

type MyStruct struct {
	A int `json:"a"`
}
obj := MyStruct{} // I need to create an object of this struct first
fmt.Println(reflect.TypeOf(obj).Field(0).Tag.Get("json"))
fmt.Println(reflect.TypeOf(obj).Field(0).Type)

What did you expect to see?

I can get reflect.Type via 'MyStruct' itself, but not it's instance.
I only want to get the member's tag and type, if I need to create an object of this class first, it looks strange

What did you see instead?

I can get reflect.Type via 'MyStruct' itself, but not it's instance.
I only want to get the member's tag and type, if I need to create an object of this class first, it looks strange

[randall77]

You can do this:

fmt.Println(reflect.TypeOf(MyStruct{}).Field(0).Tag.Get("json"))
fmt.Println(reflect.TypeOf(MyStruct{}).Field(0).Type)

It may look strange, but that's what you need to do to get a type. Types aren't first-class types in Go, you need to start with a value and ask reflect to find its type.

Do you have some concrete proposal for how it should work instead?

[mdempsky]

I don't think there's any action here.