输入类型后，不能再混合

config.Config has a method func String(string) string and I want to mix those methods to my Type Config 1. it is ok when

// type Config struct
type Config struct {
    // a struct has many methods
    config.Config
    Path string
}
// new and call string method
var a Config = &Config{}
a.String("test")

2. it not ok when

// type Config struct
type (
   Configure config.Config
   Config struct {
       Configure
       Path string
   }
)
// new and call string method
var a Config = &Config{}
// error, can not call `String()`
a.String("test")

It's well put by https://go101.org/article/type-system-overview.html:

a new defined type and its respective source type in type definitions are two distinct types.

This works:

package main

import(
  "fmt"
)

type MyType struct {
  Id int
}

func (mt *MyType)Method() {
  fmt.Printf("Method called %d
", mt.Id)
}

type MyOtherType MyType

func main(){
  mt := &MyType{Id:3}
  mt.Method()
  //mt2 := &MyOtherType{Id:5}
  //mt2.Method()
}

But if you uncomment mt2.Method(), you get an error:

mt2.Method undefined (type *MyOtherType has no field or method Method)

Composition works differently. A struct does get the methods of the structs of which it's composed:

package main

import (
    "fmt"
)

type MyType struct {
    Id int
}

func (mt *MyType) Method() {
    fmt.Printf("Method called %d
", mt.Id)
}

type MyOtherType struct {
    MyType
}

func main() {
    mt := &MyType{Id: 3}
    mt.Method()
    mt2 := &MyOtherType{MyType{Id: 5}}
    mt2.Method()
}

That's the magic of type composition.

$ go run t.go
Method called 3
Method called 5