php代码

1.

<?php
class Person 
{
    const COUNT = 10;
}

$p = 'Person';
echo $p::COUNT;//10  通过变量，调用类中的属性
echo '<br/>';//PHP_EOL并没有显示换行效果
echo Person::COUNT;//10

2.

/**
 * 普通成员，只能由对象调用
 * 静态方法，对象和类皆可调用
 * 静态属性，只能由类调用
 */
class Person
{
    public static $age = 20;
    public $sex = 1;
    function eat()
    {
        return self::$age;
    }

    static function say()
    {
        return self::$age;
    }
}

echo Person::eat();//Deprecated报错 同时输出结果 20
echo '<br/>';
$p = new Person;
echo $p->eat();//20
echo '<br/>';
echo $p->say();//20
echo '<br/>';
echo Person::say();//20
echo '<br/>';
//echo Person::$sex;//Error
echo '<br/>';
echo $p->sex;//1
echo '<br/>';
echo Person::$age;//20
echo '<br/>';
echo $p->age;//Notice报错

3.

/**
 * 接口的常量不能被子类或子接口覆盖
 * 类的常量可以
 */
class Person
{
    const AGE = 28;
}

class Male extends Person
{
    const AGE = 29;
}

echo Person::AGE;//28
echo '<br />';
echo Male::AGE;//29

interface Product
{
    const PRICE = 100;
}

interface Bike extends Product
{
    const PRICE = 200;
}

class MountainBike implements Product
{
    const PRICE = 300;
}

class PhoenixBike implements Bike
{
    
}

//echo  MountainBike::PRICE;//FATAL
echo  PhoenixBike::PRICE;//FATAL

4.

/**
 * 两个trait在同一个类中存在重名方法时，解决冲突的方式
 */
trait A
{
    function one()
    {
        return 'A';
    }
}

trait B
{
    function one()
    {
        return __CLASS__;
    }
}

class C
{
    use A,B {
        A::one insteadOf B;
        B::one as two;
    }
}

$c = new C;
echo $c->one();//A
echo '<br/>';
echo $c->two();//C

5.

/**
 * 修改trait方法的访问权限
 */
trait A
{
    function one()
    {
        return __CLASS__;
    }
}

class B
{
    use A;
}

class C
{
    use A {
        one as private two;
    }
}

$b = new B;
echo $b->one();//B
echo '<br/>';
$c = new C;
echo $c->one();//C
echo $c->two();//Error

6.

/**
 * 静态变量
 */
trait A
{
    function inc()
    {
        static $o = 0;
        $o++;
        echo "$o<br/>";
    }
}

class B
{
    use A;
}

class C
{
    use A;
}

$b = new B;
$b->inc();//1
$b->inc();//2
$b2 = new B;
$b2->inc();//3
$c = new C;
$c->inc();//1

7.

/**
 * 匿名类
 */
class A
{
    private $pri = 2;
    protected $pro = 3;

    protected function func()
    {
        return 4;
    }

    public function func2()
    {
        return new class($this->pri) extends A
        {
            private $pri2;

            function __construct($prop)
            {
                $this->pri2 = $prop;
            }

            function func3()
            {
                return $this->pro + $this->pri2 + $this->func();
            }
        };
    }
}

echo (new A)->func2()->func3();//9

8.

/**
 * 魔术方法 __call和__callStatic
 */
class A
{
    function __call($name, $params)
    {
        echo '方法名是' . $name . ',参数为：';
        var_dump($params);
    }

    /**
     * 去掉static,会有Warning报错
     */
    static function __callStatic($name, $params)
    {
        echo '静态方法名是' . $name . ',参数为：';
        var_dump($params);
    }
}

$a = new A;
$a->say(1, 2);

A::say(['3', '4']);

/* 
方法名是say,参数为：
F:\wamp\www\test.php:7:
array (size=2)
  0 => int 1
  1 => int 2
静态方法名是say,参数为：
F:\wamp\www\test.php:13:
array (size=1)
  0 => 
    array (size=2)
      0 => string '3' (length=1)
      1 => string '4' (length=1) 
*/