The specific application of PHP5 magic function explain _php tutorial

In PHP5 Magic Function 1,__construct () when an object is instantiated, this method of the object is called first.

 
  
  

  
   
   
Class Test 
  
   
   
{ 
  
   
   
function __construct () 
  
   
   
{ 
  
   
   
 echo "before"; 
  
   
   
} 
  
   
   
} 
  
   
   
$ T  New  Test (); 
 
  
  

The output is:

Start

We know that the PHP5 object model and the same class name function are the constructors of the class, so if we define both the constructor and the __construct () method, PHP5 will call the constructor by default instead of calling the __construct () function, so __construct () As the default constructor for a class

PHP5 Magic Function 2,__destruct () invokes the method when an object or object operation is terminated.

 
  
  

  
   
   
Class Test 
  
   
   
{ 
  
   
   
function __destruct () 
  
   
   
{ 
  
   
   
 echo "End"; 
  
   
   
} 
  
   
   
} 
  
   
   
$ T  New
 
  
  

will be output

End

We can do things like freeing resources at the end of an object operation.

PHP5 Magic Function 3,__get () is called when attempting to read a property that does not exist.

If you try to read a property that does not exist for an object, PHP will give you an error message. If you add a __get method to a class, and we can use this function to implement various actions like reflection in Java

 
  
  

  
   
   
Class Test 
  
   
   
{ 
  
   
   
Public Function __get ($key) 
  
   
   
{ 
  
   
   
 Echo $key. "does not exist"; 
  
   
   
} 
  
   
   
} 
  
   
   

  
   
   

  
   
   
$ T  New  Test (); 
  
   
   
Echo $t- > name; 
  
   
   

  
   
   
It will output: 
  
   
   
Name does not exist 
 
  
  

PHP5 Magic Function 4,__set () is called when attempting to write a value to a property that does not exist.

 
  
  
 
   
   
   class Test   
 
   
   
  { 
 
   
   
  public function __set ($key, $value)  
 
   
   
  { 
 
   
   
  Echo ' pair '. $key. "Attached value". $value;  
 
   
   
 }  
 
   
   
 }  
 
   
   
   
 
   
   
   
 
   
   
  $  t   =  new   Test ();  
 
   
   
  $t-  ;   name   =   "Aninggo"  ;  
 
   
   
   
 
   
   
  output:  
 
   
   
  to name appended value Aninggo  
 
  
  
 

PHP5 Magic Function 5,__call () Call this method when attempting to invoke a method that does not exist for an object.

 
  
  

  
   
   
Class Test 
  
   
   
{ 
  
   
   
Public Function __call ($Key, $Args) 
  
   
   
{ 
  
   
   
 echo "The {$Key} method you are calling does not exist. The parameter you passed in is: ". Print_r ($Args, true); 
  
   
   
} 
  
   
   
} 
  
   
   

  
   
   
$ T  New  Test (); 
  
   
   
$t- > GetName (Aning,go); 
 
  
  

The program will output:

The GetName method you are calling does not exist. parameter is: Array

(

[0] = aning

[1] = = Go

)

PHP5 Magic Function 6,__tostring () is called when printing an object

This method is similar to the ToString method of Java, when we directly print the object callback with this function

 
  
  

  
   
   
Class Test 
  
   
   
{ 
  
   
   
Public Function __tostring () 
  
   
   
{ 
  
   
   
 Return "Print Test"; 
  
   
   
} 
  
   
   
} 
  
   
   

  
   
   

  
   
   
$ T  New  Test (); 
  
   
   

  
   
   
Echo $t; 
 
  
  

When the Echo $t is run, $t->__tostring () is called and the output

Print Test

PHP5 Magic Function 7,__clone () is called when the object is cloned

 
  
  

  
   
   
Class Test 
  
   
   
{ 
  
   
   

  
   
   
Public Function __clone () 
  
   
   
{ 
  
   
   
 echo "I've been copied!" "; 
  
   
   
} 
  
   
   
} 
  
   
   

  
   
   
$ T  New  Test (); 
  
   
   
$ T1  clone  $t; 
  
   
   

  
   
   
Program output: 
  
   
   

 
  
  

PHP5 Magic function 8. By the way, some of the very cool experimental functions provided in PHP5 are

(1) runkit_method_rename

This function can dynamically change the name of the function we call.

 
  
  
 
   
   
   class Test   
 
   
   
  { 
 
   
   
   
 
   
   
  function foo () { 
 
   
   
  return "Foo!";  
 
   
   
 }  
 
   
   
   
 
   
   
 } 
 
   
   
   
 
   
   
  runkit_method_rename ( 
 
   
   
< span> ' Test ',//class name 
 
   
   
  ' foo ',//function actually called  
 
   
   
  ' Ba R '//display called function  
 
   
   
 
 
   
   
   
 
   
   
  Echo Test::bar ();  
 
   
   
   
 
   
   
  program outputs  
 
   
   
  
 
   
   
  foo! 
 
  
  

(2) Runkit_method_add

This PHP5 magic function can dynamically add functions to a class

 
 

  
  

  
Class Test
  
  

  
{
  
  

  

  
  

  
function foo () {
  
  

  
return "Foo!";
  
  

  
}
  
  

  

  
  

  
}
  
  

  

  
  

  
Runkit_method_add (
  
  

  
Test,//class name
  
  

  
' Add ',//new function name
  
  

  
' $num 1, $num 2 ',//parameters passed in
  
  

  
' Return $num 1 + $num 2; ',//code executed
  
  

  
Runkit_acc_public
  
  

  
);
  
  

  

  
  

  
Call
  
  

  
Echo $e- > Add (4);
 
 

(3) runkit_method_copy

You can copy the functions in Class A to Class B and rename the PHP5 magic function

 
  
  

  
   
   
Class Foo { 
  
   
   
 function Example () { 
  
   
   
 return "Foo!"; 
  
   
   
 } 
  
   
   
} 
  
   
   

  
   
   
Class Bar { 
  
   
   
 Empty class 
  
   
   
} 
  
   
   

  
   
   
Execute copy 
  
   
   
Runkit_method_copy (' Bar ', ' baz ', ' Foo ', ' example '); 
  
   
   

  
   
   
function after the copy is executed 
  
   
   
Echo Bar::baz (); 
 
  
  

(4) Runkit_method_redefine

Dynamically changing the return value of a function

This PHP5 magic function allows us to easily implement mock tests of classes! Isn't it cool?

2. class Example {
4. function foo () {
6. return "foo!";
8. }
10. }
14. //Create a Test object
16. $ e = New Example ();
20. //output before testing the object
22. echo "Before:". $e->foo ();
26. //Modify return value
28. Runkit_method_redefine (
30. ' Example ',
32. ' foo ',
34. '',
36. ' return ' bar!; ',
38. Runkit_acc_public
40. );
44. //Execution Output
46. echo "After:". $e->foo ();

(5) Runkit_method_remove

This PHP5 magic function is very simple, see the name can be seen, the dynamic removal of the function from the class

 
 

  
  
 
   
   class Test {  
 
   
  function foo () { 
 
   
  return "Foo!";  
 
   
 }  
 
   
   
 
   
  Fun Ction Bar () { 
 
   
  return "bar!";  
 
   
 }  
 
   
 }  
 
   
   li> 
 
   
 //remove foo function  
 
   
  Runkit_method_remove ( 
 
   
  ' Test ',  
 
   
  ' foo '  
 
   
 );  
 
   
   
 
   
  Echo implode (', Get_class_methods (' Test '));  
 
   
   
 
   
  program output  
 
   
  bar  
 
  
 
 

The code described above is about how the PHP5 magic function is applied.

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