php虚方法怎么实现-PHP问题

php虚办法的完成：起首创立一个PHP示例文件；而后经过“<?php public function x() { echo "A::x() was called.\n"; public function y(){...}}”形式完成虚函数。

保举：《PHP视频教程》

PHP5中虚函数的完成办法分享

学过C++的人都应该晓得C++中有个虚函数的概念。而正在php5中若何完成这个虚函数呢？

请看上面的代码：

代码以下:

<?php 
class A { 
public function x() { 
echo "A::x() was called.\n"; 
} 
public function y() { 
self::x(); 
echo "A::y() was called.\n"; 
} 
public function z() { 
$this->x(); 
echo "A::z() was called.\n"; 
} 
} 
class B extends A { 
public function x() { 
echo "B::x() was called.\n"; 
} 
} 
$b = new B(); 
$b->y(); 
echo "--\n"; 
$b->z(); 
?>

该例中，A::y()挪用了A::x()，而B::x()笼罩了A::x()，那末当挪用B::y()时，B::y()应该挪用A::x()仍是 B::x()呢？正在C++中，假如A::x()未被界说为虚函数，那末B::y()（也就是A::y()）将挪用A::x()，而假如A::x()应用 virtual要害字界说成虚函数，那末B::y()将挪用B::x()。

但是，正在PHP5中，虚函数的性能是由 self 以及 $this 要害字完成的。假如父类中A::y()中应用 self::x() 的形式挪用了 A::x()，那末正在子类中不管A::x()能否被笼罩，A::y()挪用的都是A::x()；而假如父类中A::y()应用 $this->x() 的形式挪用了 A::x()，那末假如正在子类中A::x()被B::x()笼罩，A::y()将会挪用B::x()。

上例的运转后果以下：

A::x() was called. A::y() was called. --
B::x() was called. A::z() was called.
virtual-function.php

代码以下:

<?php 
class ParentClass { 
static public function say( $str ) { 
static::do_print( $str ); 
} 
static public function do_print( $str ) { 
echo "<p>Parent says $str</p>"; 
} 
} 
class ChildClass extends ParentClass { 
static public function do_print( $str ) { 
echo "<p>Child says $str</p>"; 
} 
} 
class AnotherChildClass extends ParentClass { 
static public function do_print( $str ) { 
echo "<p>AnotherChild says $str</p>"; 
} 
} 
echo phpversion(); 
$a=new ChildClass(); 
$a->say( 'Hello' ); 
$b=new AnotherChildClass(); 
$b->say( 'Hello' );

以上就是php虚办法怎样完成的具体内容，更多请存眷资源魔其它相干文章！