Go Interfaces Type Assertion
Example
You can access the real data type of interface with Type Assertion.
interfaceVariable.(DataType)
Example of struct MyType which implement interface Subber:
package main
import (
"fmt"
)
type Subber interface {
Sub(a, b int) int
}
type MyType struct {
Msg string
}
//Implement method Sub(a,b int) int
func (m *MyType) Sub(a, b int) int {
m.Msg = "SUB!!!"
return a - b;
}
func main() {
var interfaceVar Subber = &MyType{}
fmt.Println(interfaceVar.Sub(6,5))
fmt.Println(interfaceVar.(*MyType).Msg)
}
Without .(*MyType) we wouldn't able to access Msg Field. If we try interfaceVar.Msg it will show compile error:
interfaceVar.Msg undefined (type Subber has no field or method Msg)
