《PHP与MySQL程序设计》第六章

用_ _set()方法设置属性

boolean __set([string property_name] , [mixed value_to_assign])

自己写了个容易理解的

<?php
class Employee
{
    var $name;
    function __set($propName, $propValue)
    {
        echo ‘$name =‘ . $this->name . ‘<br/>‘;
        echo ‘$propName = ‘ . $propName . ‘<br/>‘;
        echo ‘$propValue = ‘ . $propValue . "<br/>";

        $this->$propName = $propValue;
    }

}

$employee = new Employee();
$employee->name = "Mario";
$employee->title = "Exective chef";

echo $employee->title;

//输出
// $name =Mario
// $propName = title
// $propValue = Exective chef

__set()方法是默认的，我测试了一下，我不写__set()方法，也可以实现

$employee->sex = ‘M‘;

echo $employee->sex;

__set()的方法可以限制一些属性的设置，比如：

<?php
class Employee
{
    var $name;
    function __set($propName, $propValue)
    {
        if ($propName == ‘age‘) {
            if ($propValue < 18 || $propValue > 60) {
                $this->$propName = null;
            } else {
                $this->$propName = $propValue;
            }
        } else {
            $this->$propName = $propValue;
        }
    }
}

$employee = new Employee();
$employee->name = "Mario";
$employee->age = "17";
$employee->page = 1;

echo ‘name = ‘ . $employee->name . ‘<br/>‘;
echo ‘age = ‘ . $employee->age . ‘<br/>‘;
echo ‘page = ‘ . $employee->page;

//输出 雇员的年龄小于18或大于60的时候age=null
// name = Mario
// age =
// page = 1

boolean __get([string property_name])

测试

结论：

当属性存在的时候，__set()和__get()是不仅过的。测试例子如下->

<?php
class Employee
{
    public $name;
    public $city;
    protected $wage;

    function __set($propName, $propValue)
    {
        echo "__set called!<br/>";$this->$propName = $propValue;
    }

    function __get($propName)
    {
        echo "__get called!<br/>";
        $vars = array(
            "name",
            "city"
        );

        if (in_array($propName, $vars)) {
            return $this->$porpName;
        } else {
            return "No such variable!";
        }
    }

}

$employee = new Employee();
$employee->name = "Mario";
$employee->city = "shan";

echo $employee->name . "<br/>";
echo $employee->city . "<br/>";

// 输出
// Mario
// shan

在下面加入下的代码->

$employee->age = 20;
echo $employee->age . "<br/>";
// 输出
// __set called!
// 20

echo $employee->sex . "<br/>";
//输出
// __get called!
// No such variable!

如果在$vars数组中加入sex的话，程序报错！

看下来感觉没什么亮点，用不起来。