// Package structs is for manipulating structures with reflectionpackage structs import (	"reflect") // SetFrom sets the public members of a from b//// a and b should be pointers to structs//// a can be a different type from b//// Only the Fields which have the same name and assignable type on a// and b will be set.//// This is useful for copying between almost identical structures that// are requently present in auto generated code for cloud storage// interfaces.func SetFrom(a, b interface{}) {	ta := reflect.TypeOf(a).Elem()	tb := reflect.TypeOf(b).Elem()	va := reflect.ValueOf(a).Elem()	vb := reflect.ValueOf(b).Elem()	for i := 0; i < tb.NumField(); i++ {		bField := vb.Field(i)		tbField := tb.Field(i)		name := tbField.Name		aField := va.FieldByName(name)		taField, found := ta.FieldByName(name)		if found && aField.IsValid() && bField.IsValid() && aField.CanSet() && tbField.Type.AssignableTo(taField.Type) {			aField.Set(bField)		}	}} // SetDefaults for a from b//// a and b should be pointers to the same kind of struct//// This copies the public members only from b to a.  This is useful if// you can't just use a struct copy because it contains a private// mutex, eg as http.Transport.func SetDefaults(a, b interface{}) {	pt := reflect.TypeOf(a)	t := pt.Elem()	va := reflect.ValueOf(a).Elem()	vb := reflect.ValueOf(b).Elem()	for i := 0; i < t.NumField(); i++ {		aField := va.Field(i)		// Set a from b if it is public		if aField.CanSet() {			bField := vb.Field(i)			aField.Set(bField)		}	}}