Go reflect TypeOf and valueof

This is a creation in Article, where the information may have evolved or changed.

Learning Go's reflection is of great value in understanding the underlying implementation of go and the interface mechanism. This article from a source program to experience the go reflection of the two core functions typeof and valueof, especially the way to construct the type instance according to type.

Package Mainimport ("FMT" "reflect") type Speaker interface {Speak () Stringset (string)}type Teacher struct {Name string} Func (this *teacher) Speak () string {return this. Name}func (This *teacher) Set (name string) {this. Name = Name}func Testref (s Speaker) (t reflect. Type) {reflectval: = reflect. ValueOf (s)//t = reflect. Indirect (Reflectval). Type () T = Reflectval.elem (). Type () fmt. Printf ("reflect. ValueOf (%V). Elem (). Type () =%v\n ", s,t) Return}func TestRef2 (S Speaker) (t reflect. Type) {//t = reflect. TypeOf (s). Elem ()//fmt. Printf ("reflect. TypeOf (%V). Elem () =%v\n ", s,t) T = reflect. TypeOf (s) fmt. Printf ("reflect. TypeOf (%V) =%v\n ", s,t) Return}func TestRef3 (S *teacher) (t reflect. Type) {t = reflect. TypeOf (s). Elem () fmt. Printf ("reflect. TypeOf (%V). Elem () =%v\n ", S,t) Return}func main () {te: = &teacher{name:" NewYear ",}fmt. Printf ("source=%v\n", TE) fmt. Printf ("\ n") var tea Speaker = te T1: = Testref (TEA)//default is to create a 0 value instance, string is "" If m, OK: = reflect. New (T1). Interface (). (Speaker); OK {fmt. Printf ("reflect. New (%V).Interface (). (Speaker) =%v\n ", T1, M) fmt. Printf ("se. Speak () =%v\n ", M.speak ()) M.set (" the ") fmt. Printf ("reflect. New (%V). Interface (). (Speaker) =%v\n ", T1, M) fmt. Printf ("se. Speak () =%v\n ", M.speak ())}fmt. Printf ("Source Instance te=%v\n", TE) fmt. Printf ("\ n") t2: = TestRef2 (tea)//if m, OK: = reflect. New (T2). Interface (). (Speaker); OK {if m, OK: = reflect. New (T2. Elem ()). Interface (). (Speaker); OK {fmt. Printf ("reflect. New (%v.elem ()). Interface (). (Speaker) =%v\n ", T2, M) fmt. Printf ("se. Speak () =%v\n ", M.speak ()) M.set (" ") fmt. Printf ("reflect. New (%v.elem ()). Interface (). (Speaker) =%v\n ", T2, M) fmt. Printf ("se. Speak () =%v\n ", M.speak ())}fmt. Printf ("Source Instance te=%v\n", TE) fmt. Printf ("\ n") T3: = TESTREF3 (TE) if m, OK: = reflect. New (T3). Interface (). (Speaker); OK {fmt. Printf ("reflect. New (%V). Interface (). (Speaker) =%v\n ", T3, m) fmt. Printf ("se. Speak () =%v\n ", M.speak ()) M.set (" ") fmt. Printf ("reflect. New (%V). Interface (). (Speaker) =%v\n ", T3, m) fmt. Printf ("se. Speak () =%v\n ", M.speak ())}fmt. Printf ("Source Instance te=%v\n",TE) fmt. Printf ("\ n") fmt. Printf ("reflect. TypeOf (tea) =%v\n ", reflect. TypeOf (tea)) fmt. Printf ("reflect. TypeOf (tea). Elem () =%v\n ", reflect. TypeOf (tea). Elem ()) fmt. Printf ("reflect. ValueOf (tea) =%v\n ", reflect. ValueOf (tea)) fmt. Printf ("reflect. ValueOf (tea). Elem () =%v\n ", reflect. ValueOf (tea). Elem ()) fmt. Printf ("\ n") if SE, OK: = reflect. ValueOf (tea). Interface (). (Speaker); OK {//if SE, OK: = reflect. ValueOf (TE). Interface (). (Speaker); OK {fmt. Printf ("reflect. ValueOf (%V). Interface (). (Speaker) =%v\n ", tea, se) fmt. Printf ("se. Speak () =%v\n ", SE. Speak ()) se. Set ("") fmt. Printf ("reflect. ValueOf (%V). Interface (). (Speaker) =%v\n ", tea, se) fmt. Printf ("se. Speak () =%v\n ", SE. Speak ())}fmt. Printf ("Source Instance te=%v\n", TE) fmt. Printf ("\ n")//if se, OK: = reflect. New (reflect. TypeOf (TE). Elem ()). Interface (). (Speaker); OK {if SE, OK: = reflect. New (reflect. TypeOf (tea). Elem ()). Interface (). (Speaker); OK {fmt. Printf ("reflect. New (reflect. TypeOf (%V). Elem ()). Interface (). (Speaker) =%v\n ", Tea,se) fmt. Printf ("se. Speak () =%v\n ",Se. Speak ()) se. Set ("2018") Fmt. Printf ("reflect. New (reflect. TypeOf (%V). Elem ()). Interface (). (Speaker) =%v\n ", Tea,se) fmt. Printf ("se. Speak () =%v\n ", SE. Speak ())}fmt. Printf ("Source Instance te=%v\n", TE) fmt. Printf ("\ n") if SE, OK: = reflect. New (reflect. TypeOf (TE). Elem ()). Interface (). (Speaker); OK {fmt. Printf ("reflect. New (reflect. TypeOf (%V). Elem ()). Interface (). (Speaker) =%v\n ", Te,se) fmt. Printf ("se. Speak () =%v\n ", SE. Speak ()) se. Set ("2019") FMT. Printf ("se. Speak () =%v\n ", SE. Speak ()) fmt. Printf ("reflect. New (reflect. TypeOf (%V). Elem ()). Interface (). (Speaker) =%v\n ", Te,se)}fmt. Printf ("Source Instance te=%v\n", TE) fmt. Printf ("\ n")}