In-depth analysis of object-oriented PHP_PHP tutorial-PHP Tutorial-php.cn

In-depth analysis of object-oriented PHP_PHP tutorial

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Release： 2016-07-21 15:10:00

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In the past, object-orientation was limited to rote memorization. After working for so long, looking back, I have gained another understanding for everyone to see.
1.final
final: php5 adds a new final keyword. If a method in the parent class is declared final, the subclass cannot override the method; if a class is declared final, it cannot be inherited.

Copy code The code is as follows:

class BaseClass{
 public function test(){
 ehco "test ";
 }

 final public function moreTest(){
 echo "moretest";
 }
}

class ChildClass extends BaseClass{
 public function moreTest(){
                                                                                                                                                            Echo "moretest"; 🎜>
2.__toString (PHP5.2 or higher is recommended)

Copy code
The code is as follows:

class Person{ protected $name; protected $email; public function setName($name){

$this->name = $name ;

 }

 public function setEmail($email){
 >              return "$this->name <$this->email>";
                                                                                                                               );
$rasums->setEmail('test@qq.com');
print $rasums;

3. Interfaces and abstract classes

The role of interface: You want to ensure that a class implements one or more methods with a specific name, visibility, and prototype. 

 Interface requirements: 

 All methods in the class are abstract methods 
 There is no need to add abstract for abstract methods 
 The abstract method attributes of the interface are public

The member attributes must be Constant
Example:
Copy code
The code is as follows:
interface ChildTest{
public function childTest ();
}
class FathTest implements ChildTest1,ChildTest2{
public function childTest(){ echo 1;
}

…………} The role of abstraction: In fact, abstract classes and interface classes are partly similar. I remember where I saw this sentence, abstract classes extract the similar parts. This sentence looks funny, but in fact it says The truth about abstract classes is that the role of abstract classes is that when you find that many of your classes use many methods that you are constantly writing over and over again, then you can consider using abstract classes. You may say, "I can't repeat them." Write a class. For each public class, I instantiate one of this public class and call the same method." This is OK. In fact, this is what the abstract class does, but it saves you the need to instantiate it. Steps make it as convenient as calling the method of this class directly, and you can also overload this method.

Abstract requirements: 

 There must be at least one abstract method in the class 
 The abstract method must be added abstract

 Example: 

Copy code

The code is as follows:

abstract class Database{ abstract public function connect(); abstract public function query();
abstract public function fetch();
abstract public function close();}

Note: Abstract methods cannot be defined as private methods or final methods because they need to be inherited.

4. Pass object reference
php4: All "="s create a copy
php5: Except for objects, other "="s When assigning a value, a copy is created; while the object is a reference

5. Clone object
1.
Aggregation class :
Introduction to the __call method:
When the client code uses an undefined method in the class, __call will be called.
__call() accepts two parameters, one is the method name, and the other is all parameters (including arrays) passed to the method to be called.
Any value returned by the __call() method will be returned to the client and will be as if called The method really exists
Example:

Copy codeThe code is as follows:

class Address{
protected $city ;
protected $country;

public function setCity($city){$this->city = $city;}
public function getCity(){return $this->city;}
public function setCountry($country) {$this->country = $country;}
public function getCountry(){return $this->country;}
}

class Person{
protected $name;
protected $address;
//Shallow clone
public function __construct(){
$this->address = new Address;
}

public function setName($name){
$this->name = $name;
}
public function getName(){
return $this->name;
}

public function __call($method,$arguments){
if(method_exists($this->address,$method)){
return call_user_func_array(array($this->address,$method) ; > }
}

$test1 = new Person;
$test2 = clone $test1;

$test1->setName('testname1');
$test1->setCity('testcity1');

$test2->setName('testname2');

$test2 ->setCity('testcity2');

echo $test1->getName().'-'.$test1->getCity()."n";

echo $test2->getName().'-'.$test2- >getCity()."n";
//testname1-testcity2
//testname2-testcity2

6. Important attribute access (__set __get __isset __unset) __isset __unset is only useful after 5.1

Function: intercept the demand for attributes. In order to improve the degree of separation, __isset() and __unset() must also be implemented so that when we use isset To detect attributes or unset() to delete attributes to ensure that the behavior of the class is correct
Example:
Copy code
The code is as follows:

class Person{
protected $__data = array('email','test');

     public function __get($property){
          if(isset($this->__data[$property])){
               return $this->__data[$property];
          }else{
               return false;
          }
     }

     public function __set($property,$value){
          if(isset($this->__data[$property])){
               return $this->__data[$property] = $value;
          }else{
               return false;
          }
     }

     public function __isset($property){
          if(isset($this->__data[$property])){
               return true;
          }else{
               return false;
          }
     }

     public function __unset($property){
          if(isset($this->__data[$property])){
               return unset($this->__data[$property]);
          }else{
               return false;
          }
     }
}

$test = new Person;
$test->email= 'test';
var_dump($test->email);

注意:
     这两个方法只会捕捉缺少的属性，如果你为你的类定义了一个属性，那么当访问这个属性时php不会调用__get()和__set();
     这两个方法完全破坏了任何属性继承的想法。如果父对象中有个 __get()方法，而你在子类中又实现了自己的__get()方法，那么你的对象不会正确的执行，因为父类的__get()方法永远不会被调用，当然可以用parent::__get()解决
缺点：
     速度相对较慢
     使用魔术访问器方法就不可能在使用反射类，如phpdocumentor这类的工具将代码自动文档化
     不能将其用于静态属性