Go for PHP programmers

By Evert Pot, for GTA PHP User Group. September 2016

My journey, the last 6 months

Been very focused on PHP for most of my professional career.
Recently wrote a blog post titled 'PHP sucks'.
Disillusioned with php-fig.

What to do next?

The choice was between Go, Rust and Swift.
All are very modern, have similar properties but also big differences.
All are statically typed and compiled.

I settled on Go

Go has the least amount of features.
Go is focussed on concurrency, multi-core, networked machines.

What is Go?

A relatively new language. Open source, but from Google.
Brought to you by the people from C, Unix and UTF-8.
Still up and coming.

What is go?

It's compiled (like C).
It's statically typed (like Java).
It's managed and garbage collected (like PHP/Java).
It has great async primitives (like Erlang)
It has a weird type system (unlike anything)

Use-cases for PHP developers

You need a real-time Websocket server that scales.
You have a microservice or script that benefits from better performance.
You're writing a TCP service.
You're writing a critical component in your business logic where bugs are a big problem.

Or you can choose Java!

Just as good for thoses use-cases.
But the Java ecosystem has a problem with simplicity and conciseness.
Ignoring large frameworks is possible but counter-culture.

Choosing a language means choosing a culture

Goes beyond syntax.
Ecosystem.
Popular library choices.
Coding standards.
Application Architecture.

Lets write some Go code

package main

import (
    "fmt"
)

func main() {
    fmt.Println("Hello, PHPers")
}

The Go command-line utility

go run helloworld.go
go build
go fmt helloworld.go

Strict typing

Go

i := 5;
s := "6"

fmt.Printf("i + s: %v", i+s)
// Error

PHP

$i = 5;
$s = "6"

echo "i + s: ", $i+$si;
// 11

Function declarations

Go

func addSome(a, b int) {
    fmt.Println(a+b)
}

PHP

function addSome(int $a, int $b) {
    echo $a + $b, "\n";
}

Calling that function

addSome(5, "6 million");

Calling that function

addSome(5, "6 million");

PHP

Prints 11, and throws notice.

Calling that function

addSome(5, "6 million");

PHP

Prints 11, and throws notice.
Or throws an error if you're in strict mode.

Calling that function

addSome(5, "6 million");

PHP

Prints 11, and throws notice.
Or throws an error if you're in strict mode.

Go

Simply not a valid program

Why is this important?

In dynamic type systems you only often find this bug once the function is called with the invalid value.
In static type systems these types of bugs can simply not exist.
Static is also faster, because the check is done once, during compile.
Dynamic means that the check has to be done for every invocation.

Some more types

int
int32
int64
uint
uint32
uint64
bool
string
rune
float32

Some more types

[]int
[]int32
[]int64
[]uint
[]uint32
[]uint64
[]bool
[]string
[]rune
[]float32

Oh no, pointers

*int
*int32
*int64
*uint
*uint32
*uint64
*bool
*string
*rune
*float32

Maps!

map[string]int
map[string]uint
etc.

Structs

type Article struct {
    Id int
    Title string
    Published time.Time
    Body string
    Comments []Comment
}

Uppercase first character means 'public'

Structs

type Article struct {
    Id int
    Title string
    Published time.Time
    Body string
    Comments []Comment
}

article := Article{
    5,
    "Go for PHP programmers",
    time.Now(),
    "...",
}

Adding methods

func (a *Article) Publish() {
    a.Published = time.Now()
}

Adding methods

func (a *Article) Publish() {
    a.Published = time.Now()
}

Constructor

func NewArticle() : Article {
    // Must return an Article
}

Polymorphism

type Publishable interface {
    func Publish()
}

Polymorphism

type Publishable interface {
    func Publish()
}

func PublishThis(p Publishable) {
    p.Publish();
}

The PHP equivalent

class Article {
    public $id;
    public $title;
    public $published;
    public $body;
    function publish() {}
}

interface Publishable {
    function publish();
}

$article = new Article();
echo $article instanceof Publishable; // true!

Real example

// Adding this method satisfies the fmt.Stringer interface.
func (a Article) String() : string {
    return a.Title;
}

fmt.Printf("<h1>%v</h1>", someArticle);

Example 2

type (
    Reader interface {
        Read(p []byte) (n int, err error)
    }
    Writer interface {
         Write(p []byte) (n int, err error)
    }
    ReadWriter interface {
        Reader
        Writer
    }
}

Loops

There's only one loop keyword:

for i := 0; i < 10; i++ {
}

Loops

While

for {
    if condition {
        break;
    }
}

Loops

Foreach

for index, article := range articles {
}

Concurrency

func hi() {
    for i := 0; i < 3; i++ {
        fmt.Printf("Number %v, hahaha\n")
    }
}

hi()

Concurrency

func hi() {
    for i := 0; i < 3; i++ {
        fmt.Printf("Number %v, hahaha\n")
    }
}

go hi()

Goroutines

Like Node / Javascript co-routines.
Kind of like a Worker.
Works like an event loop.
Unlike JS, can break out to multiple CPUs

Goroutines

Are cheap
"10,000 Goroutines are normal, 100,000 not uncommon"
Should be treated as real threads!

var hits int

func addHit() {
    hits = hits + 1
}

func main() {
    hits := 0
    addHit()
}

var hits int

func addHit() {
    hits = hits + 1
}

func main() {
    hits := 0;
    go addHit()
}

var hits int
var mutex *sync.Mutex

func addHit() {
    mutex.Lock()
    hits = hits + 1
    mutex.Unlock()
}

func main() {
    hits := 0;
    mutex = &sync.Mutex{}
    go addHit()
}

var hits int64

func addHit() {
    atomic.AddInt64(hits, 1)
}

func main() {
    hits := 0
    go addHit()
}

Channels

struct Hit {
   UserAgent string
   Address string
}

hitChannel := make(chan *Hit)
hits := 0;

go func() {
    hit <- hitChannel
    hits = hits + 1;
}()

for i:=0; i < 100; i++ {
    go func() {
        hit := &Hit{"",""}
        hitsChannel <- hit
    }()
}

Selecting from multiple channels

for {
    select {
    case value1 <- channel1:
        // do something with value 1
    case value2 <- channel2:
        // do something with value 2
    }
}

PHP equivalents?

curl_multi_select
socket_select
stream_select
mysqli_poll

Error handling

dat, err := ioutil.ReadFile("file.txt")

if err != nil {
    // Handle the error
}

Error handling

dat, _ := ioutil.ReadFile("file.txt")

Error handling

dat, err := ioutil.ReadFile("file.txt")
if err != nil {
    panic(err)
}

Error handling

func ParseTextFile() (string, error) {

    dat, err := ioutil.ReadFile("file.txt")
    if err != nil {
        return nil, err
    }

    // Do something with file
    return result, nil

}

Last tips

When you're just starting off with Go, follow every suggestion in the tutorials.
PHP is great for quick prototyping, Go is less so.
You're forced to be dilligent, but this can be rewarding for mission-critical applications.
Go is simple enough for teams to pick up. Posssibly better than Node for the same use-cases.

Go for PHP programmers

My journey, the last 6 months

What to do next?

I settled on Go

What is Go?

What is go?

Use-cases for PHP developers

Or you can choose Java!

Choosing a language means choosing a culture

Lets write some Go code

The Go command-line utility

Strict typing

Go

PHP

Function declarations

Go

PHP

Calling that function

Calling that function

PHP

Calling that function

PHP

Calling that function

PHP

Go

Why is this important?

Some more types

Some more types

Oh no, pointers

Maps!

Structs

Structs

Adding methods

Adding methods

Constructor

Polymorphism

Polymorphism

The PHP equivalent

Real example

Example 2

Loops

There's only one loop keyword:

Loops

While

Loops

Foreach

Concurrency

Concurrency

Goroutines

Goroutines

Sharing state

Sharing state

Sharing state: mutexes

Sharing state: atomic

Channels

Selecting from multiple channels

PHP equivalents?

Error handling

Error handling

Error handling

Error handling

Last tips

Sources

Evert Pot

@evertp

https://evertpot.com/