Chapter 19 Object-oriented Tools_PHP Tutorial

Learning points:
1. The magic method of OOP
2. Class functions and object functions
3.OOP reflection API

PHP supports object-oriented programming through language structures such as classes and methods. It also provides extensive support for object-oriented through object-related functions and
built-in classes.

1. OOP’s magic method

PHP introduces the __autoload() built-in method to automatically include class files. __autoload() should be written as a single parameter
method. When the PHP engine encounters an attempt to instantiate an unknown class, it calls the __autoload() method and passes the class
name to it as a string parameter.

<span>function</span> __autoload(<span>$_className</span><span>) {
    </span><span>require</span> <span>$_className</span> . '.class.php'<span>;
}
</span><span>$demo</span> = <span>new</span> Computer ();

PHP uses the __call() built-in method to shield errors generated when objects call methods. When an object calls a method that does not exist, the __call() method is automatically called.

<span>private</span> <span>function</span> __call(<span>$_methodName</span>,<span>$args</span><span>) {
    </span><span>echo</span> <span>$_methodName</span>.'方法不存在'<span>;
    </span><span>print_r</span>(<span>$args</span><span>);
}
</span><span>$computer</span>->go('我',1,'知道');

PHP uses the __toString() built-in method to print the reference of an object. Objects that do not use __toString() will generate

an error, and the __toString() method will be automatically called when printing the object.

<span>class</span><span> Computer {
    </span><span>private</span> <span>function</span><span> __toString() {
        </span><span>return</span> '打印对象'<span>;
    }
}
</span><span>echo</span> <span>new</span> Computer ();

PHP can define a __clone() built-in method in the class to adjust the cloning behavior of the object. When an object is

cloned, the __clone() method is automatically executed, and the copied object can be adjusted within its method body.

<span>class</span><span> Computer {
    </span><span>public</span> <span>$_name</span><span>;
    </span><span>public</span> <span>function</span><span> __clone() {
        </span><span>$this</span>->_name = 'ibm'<span>;
    }
}
</span><span>$computer1</span> = <span>new</span><span> Computer ();
</span><span>$computer1</span>->_name = 'dell'<span>;
</span><span>$computer2</span> = <span>clone</span> <span>$computer1</span><span>;
</span><span>echo</span> <span>$computer2</span>->_name;

2. Class functions and object functions

PHP provides a series of powerful functions to detect classes and objects. In order to know which one is being used in the third-party system at runtime.

1. The class_exists() function accepts a string representing the class, checks and returns a Boolean value. If the class exists, return true,

otherwise return false.

2. The get_class() function gets the class name of the object. If it is not an object, it returns false.

<span>echo</span> <span>class_exists</span>('Computer');

3. The get_class_methods() function gets the methods (public) in the class and returns them in the form of an array.

<span>echo</span> <span>get_class</span>(<span>$computer</span>);

4. The get_class_vars() function gets the fields (public) in the class and returns them in the form of an array

<span>print_r</span>(<span>get_class_methods</span>(<span>$computer</span>));

5. The get_parent_class() function gets the parent class of the subclass, and returns false if not.

<span>print_r</span>(<span>get_class_vars</span>('Computer'));

6. The interface_exists() function determines whether the interface exists. If it exists, it returns true, otherwise it returns false.

<span>echo</span> <span>get_parent_class</span>('NoteComputer');

7. When the is_a() function determines whether the object is a class or a parent class of this type, it returns true, otherwise it returns false.

<span>echo</span> <span>interface_exists</span>('Computer');

8. The is_subclass_of() function determines whether the object is a subclass of the class and returns true, otherwise it returns false.

<span>echo</span> <span>is_a</span>(<span>$computer</span>,'Computer');

9. The method_exists() function determines whether the object's method exists and returns true, otherwise it returns false.

<span>echo</span> <span>is_subclass_of</span>(<span>$notecomputer</span>,'Computer');

<span>echo</span> <span>method_exists</span>(<span>$computer</span>,'_run');

3. Reflection API for OOP

PHP5's class and object functions do not tell us everything inside the class, but only report their public members

. To fully understand a class, you need to know its private and protected members, as well as the parameters its methods expect.

For this, use the reflection API.

1. Obtain the dump information of reflection API

2. Obtain information about PHP’s built-in class libraries

<span>$rc</span> = <span>new</span> ReflectionClass('Computer'<span>);
Reflection</span>::export(<span>$rc</span>);

3. Get an element in the class

Reflection::export(<span>new</span> ReflectionClass('Reflection'));

<span>$_rc</span> = <span>new</span> ReflectionClass('Computer'<span>);
</span><span>echo</span> <span>$_rc</span>-><span>getFileName();
</span><span>echo</span> <span>$_rc</span>->getName();

Note: The article comes from Li Yanhui’s PHP video tutorial. This article is for communication only and may not be used for commercial purposes, otherwise you will be responsible for the consequences.

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www.bkjia.comtruehttp: //www.bkjia.com/PHPjc/778693.htmlTechArticleLearning points: 1. OOP’s magic method 2. Class functions and object functions 3. OOP’s reflection API PHP passes Language constructs such as classes and methods support object-oriented programming. At the same time, it also uses object-related functions...