I try to create a generic function that accepts any struct value and create a array of that struct type. Here is the code I tried. But I get the error "t is not a type". How can I implement this.
type RegAppDB struct {
nm string
data []interface{}
}
func CreateRegTable(tbl string, rec interface{}) RegAppDB {
t := reflect.TypeOf(rec)
fmt.Println(t)
return RegAppDB{"log", []t}
}
Go does not support generics, and any attempt to do something like that is not going to work out well. In your specific case, there are a couple of key problems:
reflect.TypeOf) happens too late to use the way you're trying to do it.[]interface{}, which means the only type you can use for that field is []interface{}. []string, for example, is a different type, and cannot be assigned to that field.I took another route. Need some beautification. But this works. So now data is an array of interface and from calling function I pass pointer to structure variables to Save function.
type RegAppDB struct {
nm string
data []interface{}
cnt int
}
// CreateRegTable creates a data structure to hold the regression result
func CreateRegTable(tbl string) *RegAppDB {
return &RegAppDB{tbl, make([]interface{}, 20), 0}
}
// Save implements saving a record Regression application DB
func (rga *RegAppDB) Save(rec interface{}) error {
rga.data[rga.cnt] = rec
rga.cnt++
return nil
}
// Show implements showing the regression table
func (rga *RegAppDB) Show() error {
fmt.Println(rga.cnt)
for i := 0; i <= rga.cnt; i++ {
fmt.Println(rga.data[i])
}
return nil
}
// Compare compares two regression table for equality
func (rga *RegAppDB) Compare(rgt *RegAppDB) bool {
return reflect.DeepEqual(rga, rgt)
}
It cannot be done for a generic type. If there are a fixed number of possible types, then you can do something like the following:
type RegAppDB struct {
nm string
data interface{}
}
func CreateRegTable(rec interface{}) RegAppDB {
switch rec.(type) {
case int:
return &RegAppDB{"log", []int{}}
case string:
return &RegAppDB{"log", []string{}}
}
return nil
}
Note: Your data in RegAppDB should be of type interface{} since []int implements interface{} but not []interface{}
