Range parser in php

* Scope parser::

* 1. Purpose

* 1. Call static members (outside the class)

* 2. Call class constants

* 3. Call class members (properties/methods) covered by subclasses

* 2. Scenario

* 1. Outside the class: Only access to the class through the class name is allowed Member

* 2. Inside the class: only the following are allowed: self, parent, static

* 3. Special: Class name variables are allowed to be used to reference the class name (php5.3)

class Demo1 
{
    const HOME = '合肥';
    public static function test1()
    {
        return __METHOD__;
    }
    public static function test2()
    {
        //延迟静态绑定:后面会说到
        //static::根据上下文来决定使用哪个类来调用
        return static::test1();
    }
}
class Demo2 extends Demo1
{
    public static $name = '朱老师';
    public static function test1()
    {
        //调用本类静态成员: self::
        $res = self::$name.&#39;<br>&#39;;
        //调用父类静态成员属性: parent::
        $res .= parent::HOME.&#39;<br>&#39;;
        //调用父类静态成员方法
        $res .= parent::test1().&#39;<br>&#39;;
        $res .= __METHOD__;
        return $res;
    }
    
}

//1. Call static members of the class from outside the class

echo Demo1::HOME,&#39;<br>&#39;;
echo Demo1::test1();
echo &#39;<hr>&#39;;
echo Demo2::test1();
echo &#39;<hr>&#39;;

//Pay attention to the difference between Demo1 calling test2() and Demo2 calling test2()

//Demo1::test( ) Returns the running result of test1() in Demo1

echo Demo1::test2();
echo &#39;<hr>&#39;;

//Demo2::test2() Returns the running result of test1() in Demo2

echo Demo2::test2();
echo &#39;<hr>&#39;;

//php5.3, allows the use of classes Variable to call

$class = 'Demo2';
echo $class::test2();

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