php the right way

參考php the right way

代碼環境

mac OS Homebrew
PHP 5.6.20 (cli)
nginx version: nginx/1.8.1
mysql Ver 14.14 Distrib 5.7.12, for osx10.11 (x86_64) using EditLine wrapper

代碼風格

閱讀 PSR-0
閱讀 PSR-1
閱讀 PSR-2
閱讀 PSR-4
閱讀 PEAR 編碼準則
閱讀 Symfony 編碼準則
使用PHP_CodeSniffer 檢查代碼是否符合規范
使用 PHP Coding Standards Fixer自動修復語法格式

面向對象

簡單類

class SimpleClass
{
    // property declaration
    public $var = 'a default value';

    // method declaration
    public function displayVar() {
        echo $this->var;
    }
}
$a = new SimpleClass();
$b = new SimpleClass();

類是對象的模板，實例化一個類就是使用模板生產一個實際對象

$this

指向這個類的當前對象

error_reporting(false);
class A
{
    function foo()
    {
        if (isset($this)) {
            echo '$this is defined ('.get_class($this).")\n";
        } else {
            echo "\$this is not defined.\n";
        }
    }
}
class B
{
    function bar()
    {
        A::foo();
    }
}
$a = new A();
$a->foo();  // $this is defined (A)
A::foo(); //$this is not defined.

$b = new B(); 
$b->bar(); // //$this is defined (B)
B::bar(); // $this is not defined.

new 變量名（帶命名空間）

$className = 'SimpleClass';
$instance = new $className(); // 等同于 new SimpleClass()

變量賦值與引用

$instance = new SimpleClass();
$assigned   =  $instance;
$reference  = &$instance;
$instance -> var = '$assigned will have this value';
$instance = null; // $instance and $reference become null

var_dump($instance); // null
var_dump($reference); // null
var_dump($assigned); //object(SimpleClass) 1 (1) { ["var"]=>string(30) "$assigned will have this value"}

創建對象的幾種方式

class Test
{
    static public function getNew()
    {
        return new static; // new static 是返回當前對象模板實例化的變量，
    }
}
class Child extends Test  // 繼承
{}
$obj1 = new Test();
$obj2 = new $obj1; // 通過new對象實例來創建一個該類的新對象
var_dump($obj1 !== $obj2); // true

$obj3 = Test::getNew();
var_dump($obj3 instanceof Test); // true

$obj4 = Child::getNew();
var_dump($obj4 instanceof Child); // true

匿名函數

class Foo
{
    public $bar;

    public function __construct() {
        $this->bar = function() {
            return 42;
        };
    }
}

$obj = new Foo();

// as of PHP 5.3.0:
$func = $obj->bar;
echo $func() , PHP_EOL;

// alternatively, as of PHP 7.0.0:
// echo ($obj->bar)();

繼承