52 lines
1.0 KiB
Go
52 lines
1.0 KiB
Go
// For more tutorials: https://blog.learngoprogramming.com
|
|
//
|
|
// Copyright © 2018 Inanc Gumus
|
|
// Learn Go Programming Course
|
|
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
|
//
|
|
|
|
package main
|
|
|
|
import (
|
|
"fmt"
|
|
"strconv"
|
|
"time"
|
|
)
|
|
|
|
type book struct {
|
|
product
|
|
published interface{}
|
|
}
|
|
|
|
// book satisfies the fmt.Stringer
|
|
func (b *book) String() string {
|
|
p := format(b.published)
|
|
|
|
// product.String() has a pointer receiver.
|
|
// That's why you need to manually take the product's address here.
|
|
//
|
|
// If you pass: "b.product", Go would pass it as a copy to Sprintf.
|
|
// In that case, Go can't deference b.product automatically.
|
|
// It's because: b.product would be different value—a copy.
|
|
return fmt.Sprintf("%s - (%v)", &b.product, p)
|
|
}
|
|
|
|
func format(v interface{}) string {
|
|
var t int
|
|
|
|
switch v := v.(type) {
|
|
case int:
|
|
t = v
|
|
case string:
|
|
t, _ = strconv.Atoi(v)
|
|
default:
|
|
return "unknown"
|
|
}
|
|
|
|
// Mon Jan 2 15:04:05 -0700 MST 2006
|
|
const layout = "2006/01"
|
|
|
|
u := time.Unix(int64(t), 0)
|
|
return u.Format(layout)
|
|
}
|