php: Sample code sharing about access control (visibility)

Php code

<?php  
/** 
 * Define MyClass 
 */  
class MyClass  
{  
    public $public = &#39;Public&#39;;  
    protected $protected = &#39;Protected&#39;;  
    private $private = &#39;Private&#39;;  
  
    function printHello()  
    {  
        echo $this->public;  
        echo $this->protected;  
        echo $this->private;  
    }  
}  
  
$obj = new MyClass();  
echo $obj->public; // 这行能被正常执行  
echo $obj->protected; // 这行会产生一个致命错误  
echo $obj->private; // 这行也会产生一个致命错误  
$obj->printHello(); // 输出 Public、Protected 和 Private  
  
  
/** 
 * Define MyClass2 
 */  
class MyClass2 extends MyClass  
{  
    // 可以对 public 和 protected 进行重定义，但 private 而不能  
    protected $protected = &#39;Protected2&#39;;  
  
    function printHello()  
    {  
        echo $this->public;  
        echo $this->protected;  
        echo $this->private;  
    }  
}  
  
$obj2 = new MyClass2();  
echo $obj2->public; // 这行能被正常执行  
echo $obj2->private; // 未定义 private  
echo $obj2->protected; // 这行会产生一个致命错误  
$obj2->printHello(); // 输出 Public、Protected2 和 Undefined  
  
?>

Php code

<?php  
/** 
 * Define MyClass 
 */  
class MyClass  
{  
    // 声明一个公有的构造函数  
    public function construct() { }  
  
    // 声明一个公有的方法  
    public function MyPublic() { }  
  
    // 声明一个受保护的方法  
    protected function MyProtected() { }  
  
    // 声明一个私有的方法  
    private function MyPrivate() { }  
  
    // 此方法为公有  
    function Foo()  
    {  
        $this->MyPublic();  
        $this->MyProtected();  
        $this->MyPrivate();  
    }  
}  
  
$myclass = new MyClass;  
$myclass->MyPublic(); // 这行能被正常执行  
$myclass->MyProtected(); // 这行会产生一个致命错误  
$myclass->MyPrivate(); // 这行会产生一个致命错误  
$myclass->Foo(); // 公有，受保护，私有都可以执行  
  
  
/** 
 * Define MyClass2 
 */  
class MyClass2 extends MyClass  
{  
    // 此方法为公有  
    function Foo2()  
    {  
        $this->MyPublic();  
        $this->MyProtected();  
        $this->MyPrivate(); // 这行会产生一个致命错误  
    }  
}  
  
$myclass2 = new MyClass2;  
$myclass2->MyPublic(); // 这行能被正常执行  
$myclass2->Foo2(); // 公有的和受保护的都可执行，但私有的不行  
  
class Bar   
{  
    public function test() {  
        $this->testPrivate();  
        $this->testPublic();  
    }  
  
    public function testPublic() {  
        echo "Bar::testPublic\n";  
    }  
      
    private function testPrivate() {  
        echo "Bar::testPrivate\n";  
    }  
}  
  
class Foo extends Bar   
{  
    public function testPublic() {  
        echo "Foo::testPublic\n";  
    }  
      
    private function testPrivate() {  
        echo "Foo::testPrivate\n";  
    }  
}  
  
$myFoo = new foo();  
$myFoo->test(); // Bar::testPrivate   
                // Foo::testPublic  
?>

<?php
class Test
{
    private $foo;

    public function construct($foo)
    {
        $this->foo = $foo;
    }

    private function bar()
    {
        echo &#39;Accessed the private method.&#39;;
    }

    public function baz(Test $other)
    {
        // We can change the private property:
        $other->foo = &#39;hello&#39;;
        var_dump($other->foo);

        // We can also call the private method:
        $other->bar();
    }
}

$test = new Test(&#39;test&#39;);

$test->baz(new Test(&#39;other&#39;));
?>

The above routine will output:

string(5) " hello"
Accessed the private method.

The above is the detailed content of php: Sample code sharing about access control (visibility). For more information, please follow other related articles on the PHP Chinese website!