Reflection type does not have method

Question

I'm trying to use reflection in Go. Why doesn't this code list the methods? It lists the fields.

is this the problem? value interface{} I'm not sure how to pass a generic struct/class/type to a function. Normally I would just pass an Object.

(I'm totally new at this. I'm a C# programmer)

package main

import (
"fmt"
"reflect"
)

func main() {
    var B TestType = TestType{TestString: "Hello", TestNumber: 3}
    ListMethods(B)
}

func ListMethods(value interface{}) {

    fooType := reflect.TypeOf(value)

    for i := 0; i < fooType.NumMethod(); i++ {
        method := fooType.Method(i)
        fmt.Println("Method = " + method.Name)
    }

    for i := 0; i < fooType.NumField(); i++ {
        field := fooType.Field(i)
        fmt.Println("Field = " + field.Name)
        fmt.Println(reflect.ValueOf(value).Field(i))
    }
}

type TestType struct {
    TestString string
    TestNumber int
}

func (this *TestType) TestFunction() {
    fmt.Println("Test")
}

Answer 1

Because you are passing a type and you declared a method to the pointer of the type.

https://play.golang.org/p/B0NdVyxGxt

Look at this example extended from yours:

package main

import (
    "fmt"
    "reflect"
)

func main() {
    var B TestType = TestType{TestString: "Hello", TestNumber: 3}
    ListMethods(B)
}

func ListMethods(value interface{}) {

    fooType := reflect.TypeOf(value)
    ptrFooType := reflect.PtrTo(fooType)

    for i := 0; i < fooType.NumMethod(); i++ {
        method := fooType.Method(i)
        fmt.Println("Method = " + method.Name)
    }

    for i := 0; i < ptrFooType.NumMethod(); i++ {
        method := ptrFooType.Method(i)
        fmt.Println("* Method = " + method.Name)
    }

    for i := 0; i < fooType.NumField(); i++ {
        field := fooType.Field(i)
        fmt.Println("Field = " + field.Name)
        fmt.Println(reflect.ValueOf(value).Field(i))
    }
}

type TestType struct {
    TestString string
    TestNumber int
}

func (this *TestType) TestFunctionPtr() {
    fmt.Println("Test")
}

func (this TestType) TestFunction() {
    fmt.Println("Test Non Ptr")
}

Notice how the *Type can access also the Type Methods. But Type cannot access to *Type Methods.

To convert from Type to *Type I have used the reflect.PtrTo(Type).