Upload 2019.03 codelab slides and resources

Author: mingrammer

README.md

@@ -4,6 +4,15 @@ Golang Korea에서 주최하는 밋업, 세미나 및 컨퍼런스의 발표 자
 
 
 
+## Golang Korea Codelab in Seoul 2019.03
+
+> [밋업 링크](https://www.meetup.com/Seoul-Go-Meetup/events/259524407/)
+
+| 발표자   | 주제                               | 발표 자료                                                    | 코드 자료                                             |
+| -------- | ---------------------------------- | ------------------------------------------------------------ | ----------------------------------------------------- |
+| 홍혜종님 | Go 소개 및 실습                    | [Introduction to Go Programming](slides/201903/introduction-to-go-programming.pdf) | [실습 예제](resources/201903/codelab)                 |
+| 권민재님 | Go로 Google OAuth2 로그인 구현하기 | [OAuth2 Codelab](slides/201903/codelab-oauth2.pdf)           | [코드랩 링크](https://github.com/golangkorea/codelab) |
+
 ## Golang Korea MeetUp in Seoul 2019.01
 
 > [밋업 링크](https://www.meetup.com/Seoul-Go-Meetup/events/258121678/)
@@ -50,3 +59,4 @@ Golang Korea에서 주최하는 밋업, 세미나 및 컨퍼런스의 발표 자
 | -------- | ------------------------------------------------------------ | ----------------------------------------------------------------------- |
 | 유승일님 | Bazel for Go                                                 | [Bazel for Go](slides/201807/bazel-for-golang.pdf)                      |
 | 배상익님 | Golang과 웹소켓을 활용한 서버 프로그래밍 (장애 없는 서버 런칭 도전기) | [Golang과 웹소켓을 활용한 서버 프로그래밍](slides/201807/server-programming-with-golang-and-websocket.pdf) |
+

resources/201903/codelab/2_1_cross_compile

@@ -0,0 +1,10 @@
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("Hello World")
+}
+
+// GOOS=linux   GOARCH=amd64 go build 4_1_cross_compile.go
+// GOOS=windows GOARCH=amd64 go build 4_1_cross_compile.go

resources/201903/codelab/2_1_cross_compile.exe

@@ -0,0 +1,9 @@
+package main
+
+import "fmt"
+
+func main(){
+	fmt.Println("Hello world.")
+}
+
+

resources/201903/codelab/2_1_cross_compile.go

@@ -0,0 +1,9 @@
+package main
+
+import "fmt"
+
+func main(){
+	fmt.println("Hello world.")
+}
+
+

resources/201903/codelab/3_1_helloworld.go

@@ -0,0 +1,11 @@
+package main
+
+import (
+	t "text/template"
+	h "html/template"
+)
+
+func main() {
+	t.New("foo").Parse(`{{define "T"}}Hello, {{.}}!{{end}}`)
+	h.New("foo").Parse(`{{define "T"}}Hello, {{.}}!{{end}}`)
+}

resources/201903/codelab/3_2_export.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+
+	_ "github.com/go-sql-driver/mysql"
+)
+
+func main() {
+	db, err := sql.Open("mysql", "user:password@/database")
+	if err != nil {
+		panic(err.Error())  // Just for example purpose. You should use proper error handling instead of panic
+	}
+	defer db.Close()
+
+	fmt.Println(db.Ping())
+}

resources/201903/codelab/3_3_identifier.go

@@ -0,0 +1,30 @@
+package main
+
+import "fmt"
+
+//func main() {
+//	foo := 1
+//	foo := 2
+//
+//	fmt.Println(foo)
+//}
+
+//func main() {
+//	foo := 1
+//	{
+//		foo := 2
+//		fmt.Println(foo)
+//	}
+//	fmt.Println(foo)
+//}
+
+func main() {
+	//foo, bar := 1, 2
+	foo, err := someFunc()
+	waldo, err := someFunc()
+
+	fmt.Println(foo, waldo, err)
+}
+func someFunc() (int, error) {
+	return 1, nil
+}

resources/201903/codelab/3_4_blank.go

@@ -0,0 +1,11 @@
+package main
+
+import "fmt"
+
+func main(){
+	 var a [4]int
+	 b := [2]string{"Penn", "Teller"}
+	 c := [...]bool{true, false, false}
+
+	 fmt.Println(a,b,c)
+}

resources/201903/codelab/4_10_redeclaration.go

@@ -0,0 +1,11 @@
+package main
+
+import "fmt"
+
+func main(){
+	letters := []string{"a", "b", "c", "d"}
+	 var bytes  = make([]byte, 5, 10)
+	 b := make([]int, 3, 3)
+
+	fmt.Println(letters,bytes,b)
+}

resources/201903/codelab/4_11_array.go

@@ -0,0 +1,10 @@
+package main
+
+import "fmt"
+
+func main(){
+	s := make([]int, 4, 4)
+	s = append(s, 1)
+
+	fmt.Println(s,len(s),cap(s))
+}

resources/201903/codelab/4_12_slice.go

@@ -0,0 +1,12 @@
+package main
+
+import "fmt"
+
+func main(){
+	s := []int{0, 1, 2, 3, 4}
+	s = s[2:4]
+	fmt.Println(s, len(s), cap(s))
+
+	s = s[1:]
+	fmt.Println(s, len(s), cap(s))
+}

resources/201903/codelab/4_13_append.go

@@ -0,0 +1,16 @@
+package main
+
+import "fmt"
+
+func main() {
+	var m map[string]int
+	m = make(map[string]int)
+
+	names := map[string]int{
+		"rsc": 3711,
+	}
+
+	tables := make(map[string]int)
+
+	fmt.Println(m, names, tables)
+}

resources/201903/codelab/4_14_subslicing.go

@@ -0,0 +1,19 @@
+package main
+
+import "fmt"
+
+func main() {
+	m := make(map[string]int)
+
+	m["foo"] = 5 // write
+
+	_ = m["foo"] // read
+
+	foo, exist := m["foo"] // second read
+	fmt.Println(foo, exist)
+
+	//delete(m, "foo") // delete
+
+	fmt.Println(m)
+
+}

resources/201903/codelab/4_15_map.go

@@ -0,0 +1,17 @@
+package main
+
+import "fmt"
+
+type Person struct {
+	_         struct{}
+	FirstName *string
+	LastName  *string
+	Age       *int
+}
+
+func main() {
+	var h1 Person = Person{FirstName: "Hyejong", LastName: "Hong", Age: 29}
+	var h2 Person = Person{"Kwon", "Minjae", 25}
+
+	fmt.Println(h1, h2)
+}

resources/201903/codelab/4_16_map_operations.go

@@ -0,0 +1,18 @@
+package main
+
+import "fmt"
+
+type Person struct {
+	FirstName string
+	LastName  string
+	Age       int
+}
+
+func (p Person) Major() bool { return p.Age >= 18 }
+func (p *Person) Birthday() { p.Age++ }
+
+func main(){
+	var h1 Person = Person{FirstName:"Hyejong", LastName:"Hong",Age:17}
+	h1.Birthday()
+	fmt.Println(h1.Major())
+}

resources/201903/codelab/4_17_struct.go

@@ -0,0 +1,15 @@
+package main
+
+import "fmt"
+
+type Person struct {
+	FirstName string
+	LastName  string
+	string
+}
+
+func main() {
+	var h1 Person = Person{FirstName: "Hyejong", LastName: "Hong", string: "2323"}
+	h1.string = "14141"
+	fmt.Println(h1)
+}

resources/201903/codelab/4_18_method.go

@@ -0,0 +1,21 @@
+package main
+
+import "fmt"
+
+func intSeq() func() int {
+	i := 0
+	return func() int {
+		i++
+		return i
+	}
+}
+
+func main(){
+	nextInt := intSeq()
+	fmt.Println(nextInt())
+	fmt.Println(nextInt())
+	fmt.Println(nextInt())
+
+	newInts := intSeq()
+	fmt.Println(newInts())
+}

resources/201903/codelab/4_19_embedding.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"fmt"
+	"reflect"
+)
+
+type T struct {
+	f1     string "f one"
+	f2, f3 int64  `f four and five`
+	f4     string `one:"1"`
+}
+
+func main() {
+	t := reflect.TypeOf(T{})
+	f1, _ := t.FieldByName("f1")
+	fmt.Println(f1.Tag) // f one
+
+	f2, _ := t.FieldByName("f2")
+	f3, _ := t.FieldByName("f3")
+	fmt.Println(f2.Tag, f3.Tag) // f four and five
+
+	f4, _ := t.FieldByName("f4")
+	fmt.Println(f4.Tag) // one:"1"
+
+	v, ok := f4.Tag.Lookup("one")
+	fmt.Printf("%s, %t\n", v, ok) // 1, true
+}

resources/201903/codelab/4_1_closure.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+type T struct {
+	F1 int `json:"f1"`
+	F2 int `json:"F2"`
+	F3 int `json:"-"`
+}
+
+func main() {
+	t := T{1, 0,  3}
+	b, err := json.Marshal(t)
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("%s\n", b) // {"f1":1,"F2":0}
+}

resources/201903/codelab/4_20_tag.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+"encoding/json"
+"fmt"
+)
+
+type T struct {
+	F1 int `json:"f1"`
+	F2 int `json:"F2"`
+	F3 int `json:"-"`
+}
+
+func main() {
+	b := []byte(`{"f1":1,"F2":2, "F3":3}`)
+	t := T{}
+	if err := json.Unmarshal(b, &t); err != nil {
+		panic(err)
+	}
+	fmt.Println(t) // {1 2 0}
+}

resources/201903/codelab/4_21_json_marshal.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+)
+
+type Stringer interface {
+	String() string
+}
+
+type Stringer2 interface {
+	String() string
+}
+
+type Binary uint64
+
+func (i Binary) String() string {
+	return strconv.FormatUint(uint64(i), 2)
+}
+
+func main() {
+	b := Binary(200)
+
+	s := Stringer(b)
+	fmt.Println(s.String())
+
+	b2, ok := s.(Binary) // interface value -> concrete value
+	if ok != false {
+		fmt.Println(b2, ok)
+
+	}
+}