Inheriting and reusing through structs and interfaces in Go

interface3.go

package main
 
import(
    	"fmt"
    	"io/ioutil"
    	"os"
)
 
type Greeter interface {
	Greet()
}
 
type Man struct {
	language string
	
	// other factors to decide if the girl would like you (for fun)
	lame, nationality, build, eye_color string
	age, height uint8
	// you could be in debt, so we can't rule out negative values
	income int64
	// this is to remind her you are available
	married	bool
}

type Woman struct {
	// Woman now has Man's fields, with her own one
	Man
	hair_style string
}
 
func (m Man) Greet() {
	switch m.language {
	case "British" : fmt.Println("Good morning, dear")
	case "American": fmt.Println("Mornin' there")
	case "Japanese": fmt.Println("Ohayou Gozaimasu")
	case "Thai"    : fmt.Println("Arunsawad Krub")
	default        : fmt.Println("Good morning")
	}
}

// Additional function to let our girl friend write a love letter
func writeFile(msg string) {
	defer func() { 
		str := recover()
		fmt.Println(str)
	}()
	
	// Create and write msg to a file
	d := []byte(msg + "\n")
	f, err := os.Create("loveLetter.txt")
	defer f.Close()
	
	err = ioutil.WriteFile("loveLetter.txt", d, 0644)
	if err != nil {
		panic("File not written!")
	} else {
		// get the file's rooted path
		dir, e := os.Getwd()
		if e != nil {
			panic("Can't get the path!")
		} else {
			fmt.Printf("File written to %s", dir + "loveLetter.txt\n")
		} 
	}
}

func (w Woman) Greet() {
	// In addition to greeting by talking, a shy Woman will want to write too
	switch w.language {
	case "British" : writeFile("Good morning, dear")
	case "American": writeFile("Mornin' there")
	case "Japanese": writeFile("Ohayou Gozaimasu")
	case "Thai"    : writeFile("Arunsawad Krub")
	case "Tagalog" : writeFile("Magandang Umaga")
	default        : writeFile("Good morning")
	}
}
 
func main() {
	jay := Man{language: "Japanese"}	
	james := Man{language: "Thai"}
	john := Man{language: "British"}

	// It just happens that jennifer's newly inherited field
	// language doesn't initialize using struct literal
	// perhaps because jennifer needs to be a pointer like so
	jennifer := new(Woman)
	jennifer.language = "Tagalog"

	greeters := [...]Greeter{jay, james, john, jennifer}
	
	for i := range greeters {
		greeters[i].Greet()
	}
	// The guy greeters will print out greeting, while jennifer will write it instead
}