（二）PHP面向对象理论2

<?php class Account{
    private $user = 1 ;
    private $pwd = 2;

    public function __set($name,$value){
        echo "Setting $name to $value \r\n";
        $this ->$name = $value;
    }
    public function __get($name){
        if (!isset($this->$name)){
            echo 'no set ';
            $this->$name = 'set default value:';
        }
            return $this->$name;
    }
}
$a = new Account();
echo $a -> user;
echo "<br><br>";
$a->user = 5;
echo $a->$name;
echo "<br><br>";
echo $a->big;

<?php /*
 * 本代码没有执行成功
 */
abstract class ActiveRecord{
    protected static $table;
    protected $fieldValues;
    public $select;

    static function findById($id){
        $query = "select * from "
            .static::$table
            ." where id = $id";
        echo $query;
        return self::createDomain($query);
    }

    function __get($fieldname){
        return $this->fieldvalues[$fieldname];
    }

    static function __callStatic($method,$args){
        $field = preg_replace('/^findBy(\w*)$','${1}',$method);
        $query = "select * from "
            .static::$table
            ." where $field='$args[0]";
        return self::createDomain($query);
    }

    private static function createDomain($query){
        echo "test";
        $klass = get_called_class();
        $domain = new $klass();
        $domain->fieldvalues = array();
        $domain->select = $query;
        foreach($klass::$fields as $field => $type){
            $domain->fieldvalues[$field] = 'TODO：set from sql result';
        }
        return $domain;
    }
}

class Customer extends ActiveRecord{
    protected static $table = 'custdb';
    protected static $fields = array(
        'id' => 'int',
        'email' => 'varchar',
        'lastname' => 'varchar'
    );
    public function  __construct(){
        echo "***";
    }
}

class Sales extends ActiveRecord{
    protected static $table = 'salesdb';
    protected static $fields = array(
        'id' => 'int',
        'item' => 'varchar',
        'qty' => 'int'
    );
}
assert("select * from custdb where id = 123" == Customer::findById(123) ->select);
assert("TODO: set from sql result" == Customer::findById(123)->email);
assert("select * from salesdb where id = 321"== Sales::findById(321)->select);
assert("select * from custdb where lastname = 'Denoncourt'"== Customer::findByLastname('Denoncourt')->select);

<?php header("Content-type: text/html; charset=utf-8");
class Account{
    public $user = 1 ;
    private $pwd = 2 ;
    public function __toString(){
        return "当前对象的用户是{$this->user},密码是{$this->pwd}";
    }
}
$a = new Account();
echo $a;
echo "<br><br>";
echo PHP_EOL."===";
echo "<br><br><br>";
print_r($a);

<?php header("Content-type: text/html; charset=utf-8");
class person{
    public $name = &#39;Tom&#39;;
    public $gender;
    static $money = 10000;
    public function __construct(){
        echo "这里是父类",PHP_EOL;
    }
    public function say(){
        echo $this->name,"\tis",$this->gender,"\r\n";
    }
}

class family extends person{
    public $name;
    public $gender;
    public $age;
    static $money = 100000;
    public function __construct(){
        parent::__construct();
        echo "这里是子类",PHP_EOL;
    }

    public function say(){
        echo "<br>我说".$this->name,"\tis\t",$this->gender,",and is \t",

$this->age,PHP_EOL."<br>";
    }

    public function cry(){
        echo parent::$money,PHP_EOL;
        echo "%>-<br><br>read again".parent::say()."<br>";
    }
}

$poor = new family();
$poor->name = 'Lee';
$poor->gender = 'female';
$poor->age = 25;
$poor->say();
$poor->cry();
$poor->read();

/*
 * 疑问：
 * 我在子类上加了个方法叫read
 * 结果执行结果成了：
 * 这里是父类 这里是子类
我说Lee is female,and is 25
10000 %>-<br>在继承中，以parent指代父类，以self指代自身。以”::”(范围解析操作符)调用父类的方法。”::”操作符还用来作为类常量和静态方法的调用。<br>如果声明类成员或方法为static,就可以不实例化类而直接访问。<br>不能通过一个对象访问其中的静态成员（静态方法除外），也不能用“：：”访问一个非静态方法。<br>继承是一种“是、像”的关系，而组合一种“需要”的关系。<br>从方法复用的角度考虑，如果两个类具有很多相同的代码和方法，可以从这两个类中抽象出一个父类，提供公共方法，然后两个类作为子类。提供个性方法。<br>继承的问题：<br>a.    继承破坏封装性。<br>b.    继承是紧耦合的。<br>c.    继承扩展复杂。<br>d.    不恰当地使用继承可能违反现实世界中的逻辑。<br><pre name="code"><?php class car{
    public function addoil(){
        echo "Add oil\r\n";
    }
}

class bmw extends car{

}

class benz{
    public $car;
    public function __construct(){
        $this->car = new car;
    }
    public function addoil(){
        $this->car->addoil();
    }
}

$bmw = new bmw();
$bmw ->addoil();
$benz = new benz();
$benz->addoil();

<?php header("Content-type: text/html; charset=utf-8");

class employee{
    protected  function working(){
        echo "本方法需要重载才能运行";
    }
}

class teacher extends employee{
    public function working(){
        echo "教书";
    }
}

class coder extends employee{
    public function working(){
        echo "敲代码";
    }
}

class readBooks extends employee{
    public function working(){
        echo "我不看书的！";
    }
}

function doprint($obj){
    if(get_class($obj) == &#39;employee&#39;){
        echo "error";
    }else{
        $obj->working();
    }
}

doprint(new teacher());
doprint(new coder());
doprint(new employee());

doprint(new readBooks());