Intro to Go Programming Package Creation

Go tools requires code organization in specific way for easy build, deploy your go code. The following section describes the process.

1) Create a specific directory $HOME/mygo
2) Set the environment variable GOPATH=$HOME/mygo
3) Create a unique namespace mkdir $GOPATH/src/github.com/nf

Develop your code inside the namespace

mkdir $GOPATH/src/github.com/nf/hello
cd $GOPATH/src/github.com/nf/hello
>> write your hello.go

build and install your hello.go with go install command in the current directory the binary will be installed in $GOPATH/bin directory

Lets create our own package to by used by other go program such as hello.go

mkdir $GOPATH/src/github.com/nf/string
cd $GOPATH/src/github.com/nf/string/string.go
>> write your string.go

================

package string

func Reverse(s string) string {

        b := []byte(s)

        for i:=0; i < len(s)/2; i++ {

                j := len(s)-i-1

                ch := b[i]

                b[i] = b[j]

                b[j] = ch

        }

        return (string(b))

}

===============

run go install in the string directory to create package string the output string.a will appear in 

$GOPATH/pkg/linux_amd64/github.com/nf/string.a 

Now lets use our string package in our hello.go

cd $GOPATH/src/github.com/nf/hello.go

===============

package main

import (

        "fmt"

        "github.com/nf/string"

)

func main() {

        fmt.Println(string.Reverse("Hello World!!"))

}

================

build the hello.go with go install

Cool!!

Let's write test program to test the package

cd $GOPATH/src/github.com/nf/string/

vi string_test.go

======================

package string

import "testing"

func Test(t *testing.T) {

        var tests = []struct {

                s, want string

        } {

                {"Backward", "drawkcaB"},

                {"Hello, # %", "% # ,olleH"},

                {"", ""},

        }

        for _, c:= range tests {

                got := Reverse(c.s)

                if got != c.want {

                        t.Errorf("Reverse(%q) == %q, want %q", c.s, got, c.want)

                }

        }

}

===============

run go test (If no error great, else fix the issue)