Presentation at golang meetup pune

1. burrowing through Go!!
Language Basics
Vishal Ghadge
Sourav Ray

2. Prerequisites
1. Installed go on your laptop
2. Set your GOROOT and GOPATH
3. Installed git and Hg

3. Hello world…
package main
import "fmt"
func main() {
fmt.Println("Hello, 世界")
}

4. Datatypes
Types:
bool byte complex64 complex128 error float32 float64
int int8 int16 int32 int64 rune string
uint uint8 uint16 uint32 uint64 uintptr
Constants:
true false iota ← interesting..
Zero value:
nil

5. Variables
Different ways to define and initializing variables
var counter int
var name string
var(
counter int
name string
)
counter, name := 10, "Golang"
var x int ← Global
func main() {
x = 10 ← Global
fmt.Println(x)
function()
}
func function() {
// x = 4 ← Global
x := 5 ← Local
fmt.Println(x)
}

6. Datatypes
iota: Enumeration in Golang
const (
const0 = iota
const1 = iota
const2 = iota
)
const (
const0 = iota
const1
const2
)
const (
a = 1 << iota
b = 1 << iota
c = 1 << iota
)
const (
a = 1 << iota
b
c
)
const(
bit0, mask0 = 1 << iota, 1<<iota - 1 // bit0 == 1, mask0 == 0
bit1, mask1
_, _ // skips iota == 2
bit3, mask3
)

7. Control statement
if-else block
if x > 0 {
return y
}else{
return z
}
if with initialization:
x := 1
if r := x % 2; r == 0 {
fmt.Println("Even", r)
} else {
fmt.Println("Odd", r)
}

8. Control statement
For Loop:
for init; condition; post { } ← c like for loop
for condition { } ← while loop
for { } ← Endless loop
J: for j := 0; j < 5; j++ {
for i := 0; i < 10; i++ {
if i > 5 {
break J
}
println(i)
}
}
list := []string{"a", "b", "c", "d", "e", "f"}
for k, v := range list {
fmt.Println(k, v)
}

9. Control statement
Switch case:
● No break statement
● fallthrough keyword
● “,” as or for case statement.
i := 4
switch i {
case 0:
case 2:
case 4:
fallthrough
case 8:
fmt.Println("Even")
case 1, 3, 5, 7, 9:
fmt.Println("Odd")
default:
fmt.Println("???")
}

10. Type declaration
Array type:
var arr[10]int
a:= [3]int{1,2,3}
weekEnd:=[2]string{“saturday”, “sunday”}
c:=[2][2]int{[2]int{1,2},[2]int{3,4}}

11. Type declaration
Slice
sl := make([]int, 10)
a:=[...]int{1,2,3,4,5} //array
s1:=a[m:n]
m ← starting index
n ← last index n-1
n-m ← length
//copy, append
s0 := []int{0, 1, 3, 4}
s1 := append(s0, 5) //returns new slice
n:=copy(s1,s[0,4]) //copy within limits

12. Type declaration
Struct:
type Circle struct {
x, y, r float64
}
var c Circle
c := Circle{x: 0, y: 0, r: 5}
c := shape.Circle{0, 0, 5}
//Embedded types
type Shape struct {}
func (s *Shape) Draw() {
fmt.Println("Draw like shape")
}
type Circle struct {
x, y, r float64
Shape
}

13. Type declaration
Interface:
type doubleMaker interface {
double()
}
type intImplementer int
func (i intImplementer) double() {
fmt.Println(2 * i)
}
//Embedded types
type tripleMaker interface {
triple()
}
type doubleMaker interface {
tripleMaker
double()
}

14. Type declaration
Functions:
● Scope
● Multiple return values
● Named result parameters
● Deferred code
● function as a value
● callbacks

15. Goroutines and channels
Code sample..
ready(“tea”,1) ← normal function call
go ready(“tea”,1) ← started as goroutine
ci := make(chan int) ← unbuffered channel of integers
cj := make(chan int, 0) ← unbuffered channel of integers
cs := make(chan int, 100) ← buffered channel of integers

16. Discussions...

17. Resources
Just search for golang...