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remove: _old iface

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Inanc Gumus
2019-10-30 12:39:19 +03:00
parent 32d2b45375
commit b97d5f5da9
76 changed files with 0 additions and 2645 deletions
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46
interfaces/_old/09-stringer/_handlemethods.go
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// 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/
//
// In the depths of the Go standard library's fmt package...
// Printing functions use the handleMethods method.
// Example:
// var pocket money = 10
// fmt.Println(pocket)
// the argument can be any type of value
// stores the pocket variable in the argument variable
// ^
// |
func (p *pp) handleMethods(argument interface{}) (handled bool) {
// ...
// Checks whether a given argument is an error or an fmt.Stringer
switch v := argument.(type) {
// ...
// If the argument is a Stringer, calls its String() method
case Stringer:
// ...
// pocket.String()
// ^
// |
p.fmtString(v.String(), verb)
return
}
// ...
}
/*
The original `handleMethods` code is more involved:
https://github.com/golang/go/blob/6f51082da77a1d4cafd5b7af0db69293943f4066/src/fmt/print.go#L574
-> 574#handleMethods(..)
-> 627#Stringer type check: If `v` is a Stringer, run:
-> 630#v.String()
*/

30
interfaces/_old/09-stringer/book.go
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// 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"
)
type book struct {
product
published timestamp
}
// String method makes the book an fmt.Stringer.
// The list was calling the embedded product type's String(),
// now it calls the book.String().
func (b *book) String() string {
// product.String() has a pointer receiver.
// Therefore, you need to manually take the product's address.
//
// 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 a different value, a copy.
return fmt.Sprintf("%s - (%s)", &b.product, b.published)
}

15
interfaces/_old/09-stringer/game.go
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@ -1,15 +0,0 @@
// 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
type game struct {
// game is an fmt.Stringer
// because the product is an fmt.Stringer
// and the game embeds the product
product
}

60
interfaces/_old/09-stringer/list.go
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@ -1,60 +0,0 @@
// 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"
"strings"
)
type item interface {
discount(ratio float64)
// ~~ interface embedding ~~
//
// item interface embeds the fmt.Stringer interface.
//
// Go adds the methods of the fmt.Stringer
// to this item interface.
//
// same as this:
// String() string
// fmt.Stringer
}
type list []item
// String method makes the list an fmt.Stringer.
func (l list) String() string {
if len(l) == 0 {
return "Sorry. We're waiting for delivery 🚚."
}
// use the strings.Builder when you're combining
// a long list of strings together.
var str strings.Builder
for _, it := range l {
// the builder.WriteString doesn't know about the stringer interface.
// because it takes a string argument.
// so, you need to call the String method yourself.
// str.WriteString(it.String())
// str.WriteRune('\n')
// or slower way:
// Print funcs can detect fmt.Stringer automatically.
fmt.Fprintln(&str, it)
}
return str.String()
}
func (l list) discount(ratio float64) {
for _, it := range l {
it.discount(ratio)
}
}

38
interfaces/_old/09-stringer/main.go
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@ -1,38 +0,0 @@
// 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"
func main() {
// The money type is a stringer.
// You don't need to call the String method when printing a value of it.
// var pocket money = 10
// fmt.Println(pocket)
store := list{
&book{product{"moby dick", 10}, toTimestamp(118281600)},
&book{product{"odyssey", 15}, toTimestamp("733622400")},
&book{product{"hobbit", 25}, toTimestamp(nil)},
&puzzle{product{"rubik's cube", 5}},
&game{product{"minecraft", 20}},
&game{product{"tetris", 5}},
&toy{product{"yoda", 150}},
}
store.discount(.5)
// The list is a stringer.
// The `fmt.Print` function can print the `store`
// by calling `store`'s `String()` method.
//
// Underneath, `fmt.Print` uses a type switch to
// detect whether a type is a Stringer:
// https://golang.org/src/fmt/print.go#L627
fmt.Print(store)
}

17
interfaces/_old/09-stringer/money.go
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@ -1,17 +0,0 @@
// 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"
type money float64
// String makes the money an fmt.Stringer
func (m money) String() string {
return fmt.Sprintf("$%.2f", m)
}

24
interfaces/_old/09-stringer/product.go
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@ -1,24 +0,0 @@
// 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"
type product struct {
title string
price money
}
// String makes the product an fmt.Stringer
func (p *product) String() string {
return fmt.Sprintf("%-15s: %s", p.title, p.price)
}
func (p *product) discount(ratio float64) {
p.price *= money(1 - ratio)
}

15
interfaces/_old/09-stringer/puzzle.go
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@ -1,15 +0,0 @@
// 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
type puzzle struct {
// puzzle is an fmt.Stringer
// because the product is an fmt.Stringer
// and the puzzle embeds the product
product
}

53
interfaces/_old/09-stringer/timestamp.go
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@ -1,53 +0,0 @@
// 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 (
"strconv"
"time"
)
// timestamp stores, formats and automatically prints a timestamp: it's a stringer.
type timestamp struct {
// timestamp embeds a time, therefore it can be used as a time value.
// there is no need to convert a time value to a timestamp value.
time.Time
}
// String method makes the timestamp an fmt.stringer.
func (ts timestamp) String() string {
if ts.IsZero() {
return "unknown"
}
// Mon Jan 2 15:04:05 -0700 MST 2006
const layout = "2006/01"
return ts.Format(layout)
}
// toTimestamp returns a timestamp value depending on the type of `v`.
// toTimestamp was "book.format()" before.
func toTimestamp(v interface{}) timestamp {
var t int
switch v := v.(type) {
case int:
// book{title: "moby dick", price: 10, published: 118281600},
t = v
case string:
// book{title: "odyssey", price: 15, published: "733622400"},
t, _ = strconv.Atoi(v)
default:
// book{title: "hobbit", price: 25},
return timestamp{}
}
return timestamp{
Time: time.Unix(int64(t), 0),
}
}

15
interfaces/_old/09-stringer/toy.go
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@ -1,15 +0,0 @@
// 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
type toy struct {
// toy is an fmt.Stringer
// because the product is an fmt.Stringer
// and the toy embeds the product
product
}

23
interfaces/_old/10-marshaler/book.go
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@ -1,23 +0,0 @@
// 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"
)
type book struct {
product
// Published (timestamp) knows how to print, encode and decode itself.
Published timestamp
}
func (b *book) String() string {
return fmt.Sprintf("%s - (%s)", &b.product, b.Published)
}

12
interfaces/_old/10-marshaler/game.go
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@ -1,12 +0,0 @@
// 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
type game struct {
product
}

39
interfaces/_old/10-marshaler/list.go
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@ -1,39 +0,0 @@
// 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"
"strings"
)
type item interface {
discount(ratio float64)
fmt.Stringer
}
type list []item
func (l list) String() string {
if len(l) == 0 {
return "Sorry. We're waiting for delivery 🚚."
}
var str strings.Builder
for _, it := range l {
str.WriteString(it.String())
str.WriteRune('\n')
}
return str.String()
}
func (l list) discount(ratio float64) {
for _, it := range l {
it.discount(ratio)
}
}

60
interfaces/_old/10-marshaler/main.go
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@ -1,60 +0,0 @@
// 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 (
"encoding/json"
"fmt"
"log"
)
func main() {
out := encode()
decode(out)
}
func decode(data []byte) {
// data := []byte(`[
// { "Title": "moby dick", "Price": 5, "Published": 118281600 },
// { "Title": "odyssey", "Price": 7.5, "Published": 733622400 },
// { "Title": "hobbit", "Price": 12.5, "Published": -62135596800 }
// ]`)
var books []*book
if err := json.Unmarshal(data, &books); err != nil {
log.Fatalln(err)
}
for _, b := range books {
fmt.Println(b)
}
}
func encode() []byte {
store := list{
&book{product{"moby dick", 10}, toTimestamp(118281600)},
&book{product{"odyssey", 15}, toTimestamp("733622400")},
&book{product{"hobbit", 25}, toTimestamp(nil)},
&puzzle{product{"rubik's cube", 5}},
&game{product{"minecraft", 20}},
&game{product{"tetris", 5}},
&toy{product{"yoda", 150}},
}
store.discount(.5)
// fmt.Print(store)
out, err := json.MarshalIndent(store[:3], "", "\t")
if err != nil {
log.Fatalln(err)
}
return out
// fmt.Println(string(out))
}

16
interfaces/_old/10-marshaler/money.go
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@ -1,16 +0,0 @@
// 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"
type money float64
func (m money) String() string {
return fmt.Sprintf("$%.2f", m)
}

23
interfaces/_old/10-marshaler/product.go
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@ -1,23 +0,0 @@
// 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"
type product struct {
Title string
Price money
}
func (p *product) String() string {
return fmt.Sprintf("%-15s: %s", p.Title, p.Price)
}
func (p *product) discount(ratio float64) {
p.Price *= money(1 - ratio)
}

12
interfaces/_old/10-marshaler/puzzle.go
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@ -1,12 +0,0 @@
// 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
type puzzle struct {
product
}

64
interfaces/_old/10-marshaler/timestamp.go
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@ -1,64 +0,0 @@
// 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 (
"strconv"
"time"
)
type timestamp struct {
time.Time
}
// timestamp knows how to decode itself from json.
//
// UnmarshalJSON is an implementation of the json.Unmarshaler interface.
// json.Unmarshal and json.Decode call this method.
func (ts *timestamp) UnmarshalJSON(data []byte) error {
*ts = toTimestamp(string(data))
return nil
}
// timestamp knows how to encode itself to json.
//
// MarshalJSON is an implementation of the json.Marshaler interface.
// json.Marshal and json.Encode call this method.
func (ts timestamp) MarshalJSON() (out []byte, err error) {
return strconv.AppendInt(out, ts.Unix(), 10), nil
}
func (ts timestamp) String() string {
if ts.IsZero() {
return "unknown"
}
// Mon Jan 2 15:04:05 -0700 MST 2006
const layout = "2006/01"
return ts.Format(layout)
}
func toTimestamp(v interface{}) timestamp {
var t int
switch v := v.(type) {
case int:
// book{title: "moby dick", price: 10, published: 118281600},
t = v
case string:
// book{title: "odyssey", price: 15, published: "733622400"},
t, _ = strconv.Atoi(v)
default:
// book{title: "hobbit", price: 25},
return timestamp{}
}
return timestamp{
Time: time.Unix(int64(t), 0),
}
}

12
interfaces/_old/10-marshaler/toy.go
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@ -1,12 +0,0 @@
// 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
type toy struct {
product
}

21
interfaces/_old/11-decode-toiface/book.go
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@ -1,21 +0,0 @@
// 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"
)
type book struct {
product
Published timestamp
}
func (b *book) String() string {
return fmt.Sprintf("%s - (%s)", &b.product, b.Published)
}

62
interfaces/_old/11-decode-toiface/database.go
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@ -1,62 +0,0 @@
// 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 (
"encoding/json"
"fmt"
)
// database is responsible for encoding and decoding a list.
type database struct {
list *list
}
func (db *database) UnmarshalJSON(data []byte) error {
// Provides a concrete data structure that we can use to decode.
// It is a slice of structs.
var decodables []struct {
Type string // The product type.
Item json.RawMessage // The raw item data (from database.json)
}
// First, decode the "Type" part.
// Leave the "Item" as raw json data.
if err := json.Unmarshal(data, &decodables); err != nil {
return err
}
// Decode the "Item" part for each json object.
for _, d := range decodables {
it, err := db.newItem(d.Item, d.Type)
if err != nil {
return err
}
*db.list = append(*db.list, it)
}
return nil
}
// newItem decodes and returns a product type wrapped in an item iface value.
func (*database) newItem(data []byte, itemType string) (it item, _ error) {
switch itemType {
default:
return nil, fmt.Errorf("newItem: type (%q) does not exist", itemType)
case "book":
it = new(book)
case "puzzle":
it = new(puzzle)
case "game":
it = new(game)
case "toy":
it = new(toy)
}
return it, json.Unmarshal(data, &it)
}

54
interfaces/_old/11-decode-toiface/database.json
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@ -1,54 +0,0 @@
[
{
"Type": "book",
"Item": {
"Title": "moby dick",
"Price": 10,
"Published": 118281600
}
},
{
"Type": "book",
"Item": {
"Title": "odyssey",
"Price": 15,
"Published": 733622400
}
},
{
"Type": "book",
"Item": {
"Title": "hobbit",
"Price": 25,
"Published": -62135596800
}
},
{
"Type": "puzzle",
"Item": {
"Title": "rubik's cube",
"Price": 5
}
},
{
"Type": "game",
"Item": {
"Title": "minecraft",
"Price": 20
}
},
{
"Type": "game",
"Item": {
"Title": "tetris",
"Price": 5
}
},
{
"Type": "toy",
"Item": {
"Title": "yoda",
"Price": 150
}
}
]

12
interfaces/_old/11-decode-toiface/game.go
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@ -1,12 +0,0 @@
// 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
type game struct {
product
}

40
interfaces/_old/11-decode-toiface/list.go
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@ -1,40 +0,0 @@
// 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"
"strings"
)
type item interface {
discount(ratio float64)
fmt.Stringer
}
type list []item
func (l list) String() string {
if len(l) == 0 {
return "Sorry. We're waiting for delivery 🚚."
}
var str strings.Builder
for _, it := range l {
str.WriteString(it.String())
str.WriteRune('\n')
}
return str.String()
}
func (l list) discount(ratio float64) {
for _, it := range l {
it.discount(ratio)
}
}

54
interfaces/_old/11-decode-toiface/main.go
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@ -1,54 +0,0 @@
// 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 (
"encoding/json"
"fmt"
"io/ioutil"
"log"
)
func main() {
data, err := ioutil.ReadFile("database.json")
if err != nil {
log.Fatalln(err)
}
var store list
db := database{list: &store}
if err := json.Unmarshal(data, &db); err != nil {
log.Fatalln(err)
}
fmt.Print(store)
/*
store := list{
&book{product{"moby dick", 10}, toTimestamp(118281600)},
&book{product{"odyssey", 15}, toTimestamp("733622400")},
&book{product{"hobbit", 25}, unknown},
&puzzle{product{"rubik's cube", 5}},
&game{product{"minecraft", 20}},
&game{product{"tetris", 5}},
&toy{product{"yoda", 150}},
}
out, err := json.MarshalIndent(store, "", "\t")
if err != nil {
log.Fatalln(err)
}
fmt.Println(string(out))
// store.discount(.5)
// fmt.Print(store)
*/
}

16
interfaces/_old/11-decode-toiface/money.go
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@ -1,16 +0,0 @@
// 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"
type money float64
func (m money) String() string {
return fmt.Sprintf("$%.2f", m)
}

23
interfaces/_old/11-decode-toiface/product.go
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@ -1,23 +0,0 @@
// 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"
type product struct {
Title string
Price money
}
func (p *product) String() string {
return fmt.Sprintf("%-15s: %s", p.Title, p.Price)
}
func (p *product) discount(ratio float64) {
p.Price *= money(1 - ratio)
}

12
interfaces/_old/11-decode-toiface/puzzle.go
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@ -1,12 +0,0 @@
// 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
type puzzle struct {
product
}

64
interfaces/_old/11-decode-toiface/timestamp.go
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@ -1,64 +0,0 @@
// 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 (
"strconv"
"time"
)
type timestamp struct {
time.Time
}
// timestamp knows how to decode itself from json.
//
// UnmarshalJSON is an implementation of the json.Unmarshaler interface.
// json.Unmarshal and json.Decode call this method.
func (ts *timestamp) UnmarshalJSON(data []byte) error {
*ts = toTimestamp(string(data))
return nil
}
// timestamp knows how to encode itself to json.
//
// MarshalJSON is an implementation of the json.Marshaler interface.
// json.Marshal and json.Encode call this method.
func (ts timestamp) MarshalJSON() (out []byte, err error) {
return strconv.AppendInt(out, ts.Unix(), 10), nil
}
func (ts timestamp) String() string {
if ts.IsZero() {
return "unknown"
}
// Mon Jan 2 15:04:05 -0700 MST 2006
const layout = "2006/01"
return ts.Format(layout)
}
func toTimestamp(v interface{}) timestamp {
var t int
switch v := v.(type) {
case int:
// book{title: "moby dick", price: 10, published: 118281600},
t = v
case string:
// book{title: "odyssey", price: 15, published: "733622400"},
t, _ = strconv.Atoi(v)
default:
// book{title: "hobbit", price: 25},
return timestamp{}
}
return timestamp{
Time: time.Unix(int64(t), 0),
}
}

12
interfaces/_old/11-decode-toiface/toy.go
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@ -1,12 +0,0 @@
// 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
type toy struct {
product
}

21
interfaces/_old/12-reflection/book.go
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@ -1,21 +0,0 @@
// 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"
)
type book struct {
product
Published timestamp
}
func (b *book) String() string {
return fmt.Sprintf("%s - (%s)", &b.product, b.Published)
}

82
interfaces/_old/12-reflection/database.go
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@ -1,82 +0,0 @@
// 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 (
"encoding/json"
"fmt"
"reflect"
)
type database struct {
list *list
}
func (db *database) MarshalJSON() ([]byte, error) {
type encodable struct {
Type string
Item item
}
var e []encodable
for _, it := range *db.list {
// TypeOf -> finds the dynamic type of "it"
// Elem -> returns the element type of the pointer
// Name -> returns the type name as string
t := reflect.TypeOf(it).Elem().Name()
e = append(e, encodable{t, it})
// Another way:
//
// t := fmt.Sprintf("%T", it)
//
// Uses: reflect.TypeOf(arg).String()
}
return json.Marshal(e)
}
func (db *database) UnmarshalJSON(data []byte) error {
var decodables []struct {
Type string
Item json.RawMessage
}
if err := json.Unmarshal(data, &decodables); err != nil {
return err
}
for _, d := range decodables {
it, err := db.newItem(d.Item, d.Type)
if err != nil {
return err
}
*db.list = append(*db.list, it)
}
return nil
}
// newItem decodes and returns a product type wrapped in an item iface value.
func (*database) newItem(data []byte, itemType string) (it item, _ error) {
switch itemType {
default:
return nil, fmt.Errorf("newItem: type (%q) does not exist", itemType)
case "book":
it = new(book)
case "puzzle":
it = new(puzzle)
case "game":
it = new(game)
case "toy":
it = new(toy)
}
return it, json.Unmarshal(data, &it)
}

54
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@ -1,54 +0,0 @@
[
{
"Type": "book",
"Item": {
"Title": "moby dick",
"Price": 10,
"Published": 118281600
}
},
{
"Type": "book",
"Item": {
"Title": "odyssey",
"Price": 15,
"Published": 733622400
}
},
{
"Type": "book",
"Item": {
"Title": "hobbit",
"Price": 25,
"Published": -62135596800
}
},
{
"Type": "puzzle",
"Item": {
"Title": "rubik's cube",
"Price": 5
}
},
{
"Type": "game",
"Item": {
"Title": "minecraft",
"Price": 20
}
},
{
"Type": "game",
"Item": {
"Title": "tetris",
"Price": 5
}
},
{
"Type": "toy",
"Item": {
"Title": "yoda",
"Price": 150
}
}
]

12
interfaces/_old/12-reflection/game.go
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@ -1,12 +0,0 @@
// 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
type game struct {
product
}

40
interfaces/_old/12-reflection/list.go
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@ -1,40 +0,0 @@
// 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"
"strings"
)
type item interface {
discount(ratio float64)
fmt.Stringer
}
type list []item
func (l list) String() string {
if len(l) == 0 {
return "Sorry. We're waiting for delivery 🚚."
}
var str strings.Builder
for _, it := range l {
str.WriteString(it.String())
str.WriteRune('\n')
}
return str.String()
}
func (l list) discount(ratio float64) {
for _, it := range l {
it.discount(ratio)
}
}

55
interfaces/_old/12-reflection/main.go
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@ -1,55 +0,0 @@
// 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 (
"encoding/json"
"fmt"
"log"
)
func main() {
/*
data, err := ioutil.ReadFile("database.json")
if err != nil {
log.Fatalln(err)
}
var store list
db := database{list: &store}
if err := json.Unmarshal(data, &db); err != nil {
log.Fatalln(err)
}
fmt.Print(store)
*/
store := list{
&book{product{"moby dick", 10}, toTimestamp(118281600)},
&book{product{"odyssey", 15}, toTimestamp("733622400")},
&book{product{"hobbit", 25}, unknown},
&puzzle{product{"rubik's cube", 5}},
&game{product{"minecraft", 20}},
&game{product{"tetris", 5}},
&toy{product{"yoda", 150}},
}
db := database{list: &store}
out, err := json.MarshalIndent(&db, "", "\t")
if err != nil {
log.Fatalln(err)
}
fmt.Println(string(out))
// store.discount(.5)
// fmt.Print(store)
}

16
interfaces/_old/12-reflection/money.go
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@ -1,16 +0,0 @@
// 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"
type money float64
func (m money) String() string {
return fmt.Sprintf("$%.2f", m)
}

23
interfaces/_old/12-reflection/product.go
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@ -1,23 +0,0 @@
// 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"
type product struct {
Title string
Price money
}
func (p *product) String() string {
return fmt.Sprintf("%-15s: %s", p.Title, p.Price)
}
func (p *product) discount(ratio float64) {
p.Price *= money(1 - ratio)
}

12
interfaces/_old/12-reflection/puzzle.go
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@ -1,12 +0,0 @@
// 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
type puzzle struct {
product
}

64
interfaces/_old/12-reflection/timestamp.go
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@ -1,64 +0,0 @@
// 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 (
"strconv"
"time"
)
type timestamp struct {
time.Time
}
// timestamp knows how to decode itself from json.
//
// UnmarshalJSON is an implementation of the json.Unmarshaler interface.
// json.Unmarshal and json.Decode call this method.
func (ts *timestamp) UnmarshalJSON(data []byte) error {
*ts = toTimestamp(string(data))
return nil
}
// timestamp knows how to encode itself to json.
//
// MarshalJSON is an implementation of the json.Marshaler interface.
// json.Marshal and json.Encode call this method.
func (ts timestamp) MarshalJSON() (out []byte, err error) {
return strconv.AppendInt(out, ts.Unix(), 10), nil
}
func (ts timestamp) String() string {
if ts.IsZero() {
return "unknown"
}
// Mon Jan 2 15:04:05 -0700 MST 2006
const layout = "2006/01"
return ts.Format(layout)
}
func toTimestamp(v interface{}) timestamp {
var t int
switch v := v.(type) {
case int:
// book{title: "moby dick", price: 10, published: 118281600},
t = v
case string:
// book{title: "odyssey", price: 15, published: "733622400"},
t, _ = strconv.Atoi(v)
default:
// book{title: "hobbit", price: 25},
return timestamp{}
}
return timestamp{
Time: time.Unix(int64(t), 0),
}
}

12
interfaces/_old/12-reflection/toy.go
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@ -1,12 +0,0 @@
// 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
type toy struct {
product
}

21
interfaces/_old/13-reflection-2/book.go
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@ -1,21 +0,0 @@
// 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"
)
type book struct {
product
Published timestamp
}
func (b *book) String() string {
return fmt.Sprintf("%s - (%s)", &b.product, b.Published)
}

88
interfaces/_old/13-reflection-2/database.go
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@ -1,88 +0,0 @@
// 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 (
"encoding/json"
"fmt"
"reflect"
)
type database struct {
list *list
types map[string]item // the registry of the types
}
func (db *database) MarshalJSON() ([]byte, error) {
type encodable struct {
Type string
Item item
}
var e []encodable
for _, it := range *db.list {
// TypeOf -> finds the dynamic type of "it"
// Elem -> returns the element type of the pointer
// Name -> returns the type name as string
t := reflect.TypeOf(it).Elem().Name()
e = append(e, encodable{t, it})
}
return json.Marshal(e)
}
func (db *database) UnmarshalJSON(data []byte) error {
var decodables []struct {
Type string
Item json.RawMessage
}
if err := json.Unmarshal(data, &decodables); err != nil {
return err
}
for _, d := range decodables {
it, err := db.newItem(d.Item, d.Type)
if err != nil {
return err
}
*db.list = append(*db.list, it)
}
return nil
}
func (db *database) newItem(data []byte, typ string) (item, error) {
it, ok := db.types[typ]
if !ok {
return nil, fmt.Errorf("newItem: type (%q) does not exist", typ)
}
// get the dynamic type inside "it" like *book, *game, etc..
t := reflect.TypeOf(it)
// get the pointer type's element type like book, game, etc...
e := t.Elem()
// create a new pointer value of the type like new(book), new(game), etc...
v := reflect.New(e)
// get the interface value and cast it to the item type
it = v.Interface().(item)
return it, json.Unmarshal(data, &it)
}
func (db *database) register(typ string, it item) {
if db.types == nil {
db.types = make(map[string]item)
}
db.types[typ] = it
}

54
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@ -1,54 +0,0 @@
[
{
"Type": "book",
"Item": {
"Title": "moby dick",
"Price": 10,
"Published": 118281600
}
},
{
"Type": "book",
"Item": {
"Title": "odyssey",
"Price": 15,
"Published": 733622400
}
},
{
"Type": "book",
"Item": {
"Title": "hobbit",
"Price": 25,
"Published": -62135596800
}
},
{
"Type": "puzzle",
"Item": {
"Title": "rubik's cube",
"Price": 5
}
},
{
"Type": "game",
"Item": {
"Title": "minecraft",
"Price": 20
}
},
{
"Type": "game",
"Item": {
"Title": "tetris",
"Price": 5
}
},
{
"Type": "toy",
"Item": {
"Title": "yoda",
"Price": 150
}
}
]

12
interfaces/_old/13-reflection-2/game.go
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@ -1,12 +0,0 @@
// 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
type game struct {
product
}

40
interfaces/_old/13-reflection-2/list.go
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@ -1,40 +0,0 @@
// 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"
"strings"
)
type item interface {
discount(ratio float64)
fmt.Stringer
}
type list []item
func (l list) String() string {
if len(l) == 0 {
return "Sorry. We're waiting for delivery 🚚."
}
var str strings.Builder
for _, it := range l {
str.WriteString(it.String())
str.WriteRune('\n')
}
return str.String()
}
func (l list) discount(ratio float64) {
for _, it := range l {
it.discount(ratio)
}
}

60
interfaces/_old/13-reflection-2/main.go
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@ -1,60 +0,0 @@
// 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 (
"encoding/json"
"fmt"
"io/ioutil"
"log"
)
func main() {
data, err := ioutil.ReadFile("database.json")
if err != nil {
log.Fatalln(err)
}
var store list
db := database{list: &store}
db.register("book", new(book))
db.register("game", new(game))
db.register("puzzle", new(puzzle))
db.register("toy", new(toy))
if err := json.Unmarshal(data, &db); err != nil {
log.Fatalln(err)
}
fmt.Print(store)
/*
store := list{
&book{product{"moby dick", 10}, toTimestamp(118281600)},
&book{product{"odyssey", 15}, toTimestamp("733622400")},
&book{product{"hobbit", 25}, unknown},
&puzzle{product{"rubik's cube", 5}},
&game{product{"minecraft", 20}},
&game{product{"tetris", 5}},
&toy{product{"yoda", 150}},
}
db := database{list: &store}
out, err := json.MarshalIndent(&db, "", "\t")
if err != nil {
log.Fatalln(err)
}
fmt.Println(string(out))
// store.discount(.5)
// fmt.Print(store)
*/
}

16
interfaces/_old/13-reflection-2/money.go
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@ -1,16 +0,0 @@
// 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"
type money float64
func (m money) String() string {
return fmt.Sprintf("$%.2f", m)
}

23
interfaces/_old/13-reflection-2/product.go
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@ -1,23 +0,0 @@
// 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"
type product struct {
Title string
Price money
}
func (p *product) String() string {
return fmt.Sprintf("%-15s: %s", p.Title, p.Price)
}
func (p *product) discount(ratio float64) {
p.Price *= money(1 - ratio)
}

12
interfaces/_old/13-reflection-2/puzzle.go
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@ -1,12 +0,0 @@
// 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
type puzzle struct {
product
}

64
interfaces/_old/13-reflection-2/timestamp.go
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@ -1,64 +0,0 @@
// 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 (
"strconv"
"time"
)
type timestamp struct {
time.Time
}
// timestamp knows how to decode itself from json.
//
// UnmarshalJSON is an implementation of the json.Unmarshaler interface.
// json.Unmarshal and json.Decode call this method.
func (ts *timestamp) UnmarshalJSON(data []byte) error {
*ts = toTimestamp(string(data))
return nil
}
// timestamp knows how to encode itself to json.
//
// MarshalJSON is an implementation of the json.Marshaler interface.
// json.Marshal and json.Encode call this method.
func (ts timestamp) MarshalJSON() (out []byte, err error) {
return strconv.AppendInt(out, ts.Unix(), 10), nil
}
func (ts timestamp) String() string {
if ts.IsZero() {
return "unknown"
}
// Mon Jan 2 15:04:05 -0700 MST 2006
const layout = "2006/01"
return ts.Format(layout)
}
func toTimestamp(v interface{}) timestamp {
var t int
switch v := v.(type) {
case int:
// book{title: "moby dick", price: 10, published: 118281600},
t = v
case string:
// book{title: "odyssey", price: 15, published: "733622400"},
t, _ = strconv.Atoi(v)
default:
// book{title: "hobbit", price: 25},
return timestamp{}
}
return timestamp{
Time: time.Unix(int64(t), 0),
}
}

12
interfaces/_old/13-reflection-2/toy.go
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@ -1,12 +0,0 @@
// 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
type toy struct {
product
}

21
interfaces/_old/14-io-reader/book.go
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@ -1,21 +0,0 @@
// 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"
)
type book struct {
product
Published timestamp
}
func (b *book) String() string {
return fmt.Sprintf("%s - (%s)", &b.product, b.Published)
}

91
interfaces/_old/14-io-reader/database.go
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@ -1,91 +0,0 @@
// 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 (
"encoding/json"
"fmt"
"io"
"io/ioutil"
"reflect"
)
type database struct {
list *list
types map[string]item // the registry of the types
}
// load the list by decoding the data from any data source.
func (db *database) load(r io.Reader) error {
// ReadAll reads from `r` entirely into memory.
// `data` contains the entire data in memory.
data, err := ioutil.ReadAll(r)
if err != nil {
return err
}
return json.Unmarshal(data, db)
}
func (db *database) MarshalJSON() ([]byte, error) {
type encodable struct {
Type string
Item item
}
var e []encodable
for _, it := range *db.list {
t := reflect.TypeOf(it).Elem().Name()
e = append(e, encodable{t, it})
}
return json.Marshal(e)
}
func (db *database) UnmarshalJSON(data []byte) error {
var decodables []struct {
Type string
Item json.RawMessage
}
if err := json.Unmarshal(data, &decodables); err != nil {
return err
}
for _, d := range decodables {
it, err := db.newItem(d.Item, d.Type)
if err != nil {
return err
}
*db.list = append(*db.list, it)
}
return nil
}
func (db *database) newItem(data []byte, typ string) (item, error) {
it, ok := db.types[typ]
if !ok {
return nil, fmt.Errorf("newItem: type (%q) does not exist", typ)
}
t := reflect.TypeOf(it)
e := t.Elem()
v := reflect.New(e)
it = v.Interface().(item)
return it, json.Unmarshal(data, &it)
}
func (db *database) register(typ string, it item) {
if db.types == nil {
db.types = make(map[string]item)
}
db.types[typ] = it
}

54
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@ -1,54 +0,0 @@
[
{
"Type": "book",
"Item": {
"Title": "moby dick",
"Price": 10,
"Published": 118281600
}
},
{
"Type": "book",
"Item": {
"Title": "odyssey",
"Price": 15,
"Published": 733622400
}
},
{
"Type": "book",
"Item": {
"Title": "hobbit",
"Price": 25,
"Published": -62135596800
}
},
{
"Type": "puzzle",
"Item": {
"Title": "rubik's cube",
"Price": 5
}
},
{
"Type": "game",
"Item": {
"Title": "minecraft",
"Price": 20
}
},
{
"Type": "game",
"Item": {
"Title": "tetris",
"Price": 5
}
},
{
"Type": "toy",
"Item": {
"Title": "yoda",
"Price": 150
}
}
]

12
interfaces/_old/14-io-reader/game.go
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@ -1,12 +0,0 @@
// 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
type game struct {
product
}

40
interfaces/_old/14-io-reader/list.go
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@ -1,40 +0,0 @@
// 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"
"strings"
)
type item interface {
discount(ratio float64)
fmt.Stringer
}
type list []item
func (l list) String() string {
if len(l) == 0 {
return "Sorry. We're waiting for delivery 🚚."
}
var str strings.Builder
for _, it := range l {
str.WriteString(it.String())
str.WriteRune('\n')
}
return str.String()
}
func (l list) discount(ratio float64) {
for _, it := range l {
it.discount(ratio)
}
}

66
interfaces/_old/14-io-reader/main.go
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@ -1,66 +0,0 @@
// 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"
"net/http"
)
func main() {
/*
store := list{
&book{product{"moby dick", 10}, toTimestamp(118281600)},
&book{product{"odyssey", 15}, toTimestamp("733622400")},
&book{product{"hobbit", 25}, unknown},
&puzzle{product{"rubik's cube", 5}},
&game{product{"minecraft", 20}},
&game{product{"tetris", 5}},
&toy{product{"yoda", 150}},
}
db := database{list: &store}
out, err := json.MarshalIndent(&db, "", "\t")
if err != nil {
log.Fatalln(err)
}
fmt.Println(string(out))
// store.discount(.5)
// fmt.Print(store)
*/
var store list
db := database{list: &store}
db.register("book", new(book))
db.register("game", new(game))
db.register("puzzle", new(puzzle))
db.register("toy", new(toy))
// load from a file
// f, _ := os.Open("database.json")
// db.load(f)
// f.Close()
// load from a string
// const data = `[
// { "Type": "book", "Item": { "Title": "1984", "Price": 8, "Published": -649641600 } },
// { "Type": "game", "Item": { "Title": "paperboy", "Price": 20 } }]`
// r := strings.NewReader(data)
// db.load(r)
// load from a web server
res, _ := http.Get("https://inancgumus.github.io/x/database.json")
db.load(res.Body)
res.Body.Close()
fmt.Print(store)
}

16
interfaces/_old/14-io-reader/money.go
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@ -1,16 +0,0 @@
// 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"
type money float64
func (m money) String() string {
return fmt.Sprintf("$%.2f", m)
}

23
interfaces/_old/14-io-reader/product.go
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@ -1,23 +0,0 @@
// 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"
type product struct {
Title string
Price money
}
func (p *product) String() string {
return fmt.Sprintf("%-15s: %s", p.Title, p.Price)
}
func (p *product) discount(ratio float64) {
p.Price *= money(1 - ratio)
}

12
interfaces/_old/14-io-reader/puzzle.go
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@ -1,12 +0,0 @@
// 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
type puzzle struct {
product
}

64
interfaces/_old/14-io-reader/timestamp.go
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@ -1,64 +0,0 @@
// 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 (
"strconv"
"time"
)
type timestamp struct {
time.Time
}
// timestamp knows how to decode itself from json.
//
// UnmarshalJSON is an implementation of the json.Unmarshaler interface.
// json.Unmarshal and json.Decode call this method.
func (ts *timestamp) UnmarshalJSON(data []byte) error {
*ts = toTimestamp(string(data))
return nil
}
// timestamp knows how to encode itself to json.
//
// MarshalJSON is an implementation of the json.Marshaler interface.
// json.Marshal and json.Encode call this method.
func (ts timestamp) MarshalJSON() (out []byte, err error) {
return strconv.AppendInt(out, ts.Unix(), 10), nil
}
func (ts timestamp) String() string {
if ts.IsZero() {
return "unknown"
}
// Mon Jan 2 15:04:05 -0700 MST 2006
const layout = "2006/01"
return ts.Format(layout)
}
func toTimestamp(v interface{}) timestamp {
var t int
switch v := v.(type) {
case int:
// book{title: "moby dick", price: 10, published: 118281600},
t = v
case string:
// book{title: "odyssey", price: 15, published: "733622400"},
t, _ = strconv.Atoi(v)
default:
// book{title: "hobbit", price: 25},
return timestamp{}
}
return timestamp{
Time: time.Unix(int64(t), 0),
}
}

12
interfaces/_old/14-io-reader/toy.go
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@ -1,12 +0,0 @@
// 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
type toy struct {
product
}

21
interfaces/_old/15-io-reader-composition/book.go
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@ -1,21 +0,0 @@
// 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"
)
type book struct {
product
Published timestamp
}
func (b *book) String() string {
return fmt.Sprintf("%s - (%s)", &b.product, b.Published)
}

35
interfaces/_old/15-io-reader-composition/counter.go
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@ -1,35 +0,0 @@
// 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 "io"
// counter counts the total number of bytes read.
type counter struct {
r io.Reader
n int
}
// newCounter wraps `r` and returns a *counter.
func newCounter(r io.Reader) *counter {
return &counter{r: r}
}
// Total bytes read.
func (c *counter) total() int {
return c.n
}
// Read counts the number of bytes read from the underlying reader.
func (c *counter) Read(p []byte) (n int, err error) {
n, err = c.r.Read(p) // read from the underlying reader
if n > 0 {
c.n += n // sum the number of bytes read with the total bytes counted
}
return n, err // return the number of bytes read and an error
}

112
interfaces/_old/15-io-reader-composition/database.go
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@ -1,112 +0,0 @@
// 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 (
"encoding/json"
"fmt"
"io"
"reflect"
)
type database struct {
list *list
types map[string]item
}
// load the list by decoding the data from any kind of data source.
func (db *database) load(r io.Reader) error {
return json.NewDecoder(r).Decode(db)
}
func (db *database) MarshalJSON() ([]byte, error) {
type encodable struct {
Type string
Item item
}
var e []encodable
for _, it := range *db.list {
t := reflect.TypeOf(it).Elem().Name()
e = append(e, encodable{t, it})
}
return json.Marshal(e)
}
func (db *database) UnmarshalJSON(data []byte) error {
var decodables []struct {
Type string
Item json.RawMessage
}
if err := json.Unmarshal(data, &decodables); err != nil {
return err
}
for _, d := range decodables {
it, err := db.newItem(d.Item, d.Type)
if err != nil {
return err
}
*db.list = append(*db.list, it)
}
return nil
}
func (db *database) newItem(data []byte, typ string) (item, error) {
it, ok := db.types[typ]
if !ok {
return nil, fmt.Errorf("newItem: type (%q) does not exist", typ)
}
t := reflect.TypeOf(it)
e := t.Elem()
v := reflect.New(e)
it = v.Interface().(item)
return it, json.Unmarshal(data, &it)
}
func (db *database) register(typ string, it item) {
if db.types == nil {
db.types = make(map[string]item)
}
db.types[typ] = it
}
// I put it here as a reference implementation of manually reading from a reader.
// func (db *database) loadX(r io.Reader) error {
// buf := make([]byte, 64)
//
// var (
// data []byte
// n int
// err error
// )
//
// for {
// n, err = r.Read(buf)
//
// if n > 0 {
// data = append(data, buf[:n]...)
// }
//
// if err != nil {
// break
// }
// }
//
// if err != io.EOF {
// return err
// }
// return json.Unmarshal(data, db)
// }

54
interfaces/_old/15-io-reader-composition/database.json
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@ -1,54 +0,0 @@
[
{
"Type": "book",
"Item": {
"Title": "moby dick",
"Price": 10,
"Published": 118281600
}
},
{
"Type": "book",
"Item": {
"Title": "odyssey",
"Price": 15,
"Published": 733622400
}
},
{
"Type": "book",
"Item": {
"Title": "hobbit",
"Price": 25,
"Published": -62135596800
}
},
{
"Type": "puzzle",
"Item": {
"Title": "rubik's cube",
"Price": 5
}
},
{
"Type": "game",
"Item": {
"Title": "minecraft",
"Price": 20
}
},
{
"Type": "game",
"Item": {
"Title": "tetris",
"Price": 5
}
},
{
"Type": "toy",
"Item": {
"Title": "yoda",
"Price": 150
}
}
]

BIN
interfaces/_old/15-io-reader-composition/database.json.gz
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12
interfaces/_old/15-io-reader-composition/game.go
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@ -1,12 +0,0 @@
// 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
type game struct {
product
}

40
interfaces/_old/15-io-reader-composition/list.go
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@ -1,40 +0,0 @@
// 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"
"strings"
)
type item interface {
discount(ratio float64)
fmt.Stringer
}
type list []item
func (l list) String() string {
if len(l) == 0 {
return "Sorry. We're waiting for delivery 🚚."
}
var str strings.Builder
for _, it := range l {
str.WriteString(it.String())
str.WriteRune('\n')
}
return str.String()
}
func (l list) discount(ratio float64) {
for _, it := range l {
it.discount(ratio)
}
}

96
interfaces/_old/15-io-reader-composition/main.go
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@ -1,96 +0,0 @@
// 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 (
"compress/gzip"
"fmt"
"net/http"
)
func main() {
/*
store := list{
&book{product{"moby dick", 10}, toTimestamp(118281600)},
&book{product{"odyssey", 15}, toTimestamp("733622400")},
&book{product{"hobbit", 25}, unknown},
&puzzle{product{"rubik's cube", 5}},
&game{product{"minecraft", 20}},
&game{product{"tetris", 5}},
&toy{product{"yoda", 150}},
}
db := database{list: &store}
out, err := json.MarshalIndent(&db, "", "\t")
if err != nil {
log.Fatalln(err)
}
fmt.Println(string(out))
// store.discount(.5)
// fmt.Print(store)
*/
var store list
db := database{list: &store}
db.register("book", new(book))
db.register("game", new(game))
db.register("puzzle", new(puzzle))
db.register("toy", new(toy))
// load from a file
// f, _ := os.Open("database.json")
// db.load(f)
// f.Close()
// load from a string
// const data = `[
// { "Type": "book", "Item": { "Title": "1984", "Price": 8, "Published": -649641600 } },
// { "Type": "game", "Item": { "Title": "paperboy", "Price": 20 } }]`
// r := strings.NewReader(data)
// db.load(r)
// load from a web server
// res, _ := http.Get("https://inancgumus.github.io/x/database.json")
// db.load(res.Body)
// res.Body.Close()
// decompress the reader while reading from it
// res, _ := http.Get("https://inancgumus.github.io/x/database.json.gz")
// gr, _ := gzip.NewReader(res.Body)
// db.load(gr)
// gr.Close()
// res.Body.Close()
// decompress and count the number of compressed bytes read
// res, _ := http.Get("https://inancgumus.github.io/x/database.json.gz")
// c := newCounter(res.Body) // count the bytes read
// gr, _ := gzip.NewReader(c)
// db.load(gr)
// fmt.Printf("%d bytes read.\n\n", c.total())
// gr.Close()
// res.Body.Close()
// count the number of compressed bytes read from the web server then decompress
res, _ := http.Get("https://inancgumus.github.io/x/database.json.gz")
gr, _ := gzip.NewReader(res.Body)
c := newCounter(gr)
db.load(c)
fmt.Printf("%d bytes read.\n\n", c.total())
gr.Close()
res.Body.Close()
fmt.Print(store)
}

16
interfaces/_old/15-io-reader-composition/money.go
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@ -1,16 +0,0 @@
// 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"
type money float64
func (m money) String() string {
return fmt.Sprintf("$%.2f", m)
}

23
interfaces/_old/15-io-reader-composition/product.go
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@ -1,23 +0,0 @@
// 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"
type product struct {
Title string
Price money
}
func (p *product) String() string {
return fmt.Sprintf("%-15s: %s", p.Title, p.Price)
}
func (p *product) discount(ratio float64) {
p.Price *= money(1 - ratio)
}

12
interfaces/_old/15-io-reader-composition/puzzle.go
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@ -1,12 +0,0 @@
// 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
type puzzle struct {
product
}

64
interfaces/_old/15-io-reader-composition/timestamp.go
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@ -1,64 +0,0 @@
// 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 (
"strconv"
"time"
)
type timestamp struct {
time.Time
}
// timestamp knows how to decode itself from json.
//
// UnmarshalJSON is an implementation of the json.Unmarshaler interface.
// json.Unmarshal and json.Decode call this method.
func (ts *timestamp) UnmarshalJSON(data []byte) error {
*ts = toTimestamp(string(data))
return nil
}
// timestamp knows how to encode itself to json.
//
// MarshalJSON is an implementation of the json.Marshaler interface.
// json.Marshal and json.Encode call this method.
func (ts timestamp) MarshalJSON() (out []byte, err error) {
return strconv.AppendInt(out, ts.Unix(), 10), nil
}
func (ts timestamp) String() string {
if ts.IsZero() {
return "unknown"
}
// Mon Jan 2 15:04:05 -0700 MST 2006
const layout = "2006/01"
return ts.Format(layout)
}
func toTimestamp(v interface{}) timestamp {
var t int
switch v := v.(type) {
case int:
// book{title: "moby dick", price: 10, published: 118281600},
t = v
case string:
// book{title: "odyssey", price: 15, published: "733622400"},
t, _ = strconv.Atoi(v)
default:
// book{title: "hobbit", price: 25},
return timestamp{}
}
return timestamp{
Time: time.Unix(int64(t), 0),
}
}

12
interfaces/_old/15-io-reader-composition/toy.go
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@ -1,12 +0,0 @@
// 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
type toy struct {
product
}