PHP magic examples

PHP magic examples

① _ Get/_ set: takes over the attributes of an object.

When accessing a non-existent object property:

Index. php
Copy codeThe Code is as follows:
<? Php
Define ('basedir' ,__ DIR _); // defines the root directory constant
Include BASEDIR. '/Common/Loader. php ';
Spl_autoload_register ('\ Common \ Loader: autoload ');

$ Obj = new \ Common \ Object ();

// When accessing a nonexistent object attribute in php
Echo $ obj-> title;

An error is thrown: Notice: Undefined property: Common \ Object ::$ title in D: \ practice \ php \ design \ psr0 \ index. php on line 9.

After the _ set and _ get methods are added to Common/Object. php

Object. php
Copy codeThe Code is as follows:
<? Php
Namespace Common;

Class Object {
Function _ set ($ key, $ value ){
}

Function _ get ($ key ){
}
}

Run index. php again, and no error will be reported.

Modify Common/Object. php again
Copy codeThe Code is as follows:
<? Php
Namespace Common;

Class Object {
Protected $ array = array ();

Function _ set ($ key, $ value ){
Var_dump (_ METHOD __);
$ This-> array [$ key] = $ value;
}

Function _ get ($ key ){
Var_dump (_ METHOD __);
Return $ this-> array [$ key];
}
}

Index. php
Copy codeThe Code is as follows:
<? Php
Define ('basedir' ,__ DIR _); // defines the root directory constant
Include BASEDIR. '/Common/Loader. php ';
Spl_autoload_register ('\ Common \ Loader: autoload ');

$ Obj = new \ Common \ Object ();

$ Obj-> title = 'hello ';
Echo $ obj-> title;

Run index. php and the page output is as follows:
Copy codeThe Code is as follows:
String 'common \ Object :__ set '(length = 20)
String 'common \ Object :__ get '(length = 20)
Hello

② _ Call/_ callStatic: controls the call of PHP Object methods (_ callStatic is used to control class static methods)

When executing a non-existent php Method

Index. php:
Copy codeThe Code is as follows:
<? Php
Define ('basedir' ,__ DIR _); // defines the root directory constant
Include BASEDIR. '/Common/Loader. php ';
Spl_autoload_register ('\ Common \ Loader: autoload ');

$ Obj = new \ Common \ Object ();

// When executing a non-existent php Method
$ Obj-> test ('hello', 123 );

Execute index. php reports a Fatal error: Call to undefined method Common \ Object: test () in D: \ practice \ php \ design \ psr0 \ index. php on line 9

If a _ call method is defined in Common/Object, automatic callback is triggered if the method does not exist:
Copy codeThe Code is as follows:
<? Php
Namespace Common;

Class Object {
Function _ call ($ func, $ param) {// $ func method name $ param Parameter
Var_dump ($ func, $ param );
Return "magic function \ n"; // return a string as the return value
}
}

Index. php

Copy codeThe Code is as follows:
<? Php
Define ('basedir' ,__ DIR _); // defines the root directory constant
Include BASEDIR. '/Common/Loader. php ';
Spl_autoload_register ('\ Common \ Loader: autoload ');

$ Obj = new \ Common \ Object ();

// When executing a non-existent php Method
Echo $ obj-> test ('hello', 123 );

Page output:
Copy codeThe Code is as follows:
String 'test' (length = 4)
Array
0 => string 'hello' (length = 5)
1 => int 123
Magic function

When a non-existent static method is called

Common/Object. php

Copy codeThe Code is as follows:
<? Php
Namespace Common;

Class Object {
Static function _ callStatic ($ name, $ arguments ){
Var_dump ($ name, $ arguments );
Return "magic function \ n"; // return a string as the return value
}
}

Note: __the callStatic method must also be declared as a static method.

Index. php
Copy codeThe Code is as follows:
<? Php
Define ('basedir' ,__ DIR _); // defines the root directory constant
Include BASEDIR. '/Common/Loader. php ';
Spl_autoload_register ('\ Common \ Loader: autoload ');

// Execute a non-existent static method
Echo Common \ Object: test ("hello", 1234 );

Run index. php and the page output is as follows:
Copy codeThe Code is as follows:
String 'test' (length = 4)
Array
0 => string 'hello' (length = 5)
1 => int 1234
Magic function

③ _ ToString: converts a PHP object into a string.

Index. php
Copy codeThe Code is as follows:
<? Php
Define ('basedir' ,__ DIR _); // defines the root directory constant
Include BASEDIR. '/Common/Loader. php ';
Spl_autoload_register ('\ Common \ Loader: autoload ');

$ Obj = new \ Common \ Object ();

Echo $ obj;

The following error occurs: Catchable fatal error: Object of class Common \ Object cocould not be converted to string in D: \ practice \ php \ design \ psr0 \ index. php on line 8.

Add the _ toString method to Object. php.
Copy codeThe Code is as follows:
<? Php
Namespace Common;

Class Object {
Function _ toString (){
Return _ CLASS __;
}
}

④ _ Invoke: This magic method is called back when a PHP Object is executed as a function.

Index. php
Copy codeThe Code is as follows:
<? Php
Define ('basedir' ,__ DIR _); // defines the root directory constant
Include BASEDIR. '/Common/Loader. php ';
Spl_autoload_register ('\ Common \ Loader: autoload ');

$ Obj = new \ Common \ Object ();

Echo $ obj ("test ");

Object. php
Copy codeThe Code is as follows:
<? Php
Namespace Common;

Class Object {
Function _ invoke ($ param ){
Var_dump ($ param );
Return 'invoke ';
}
}

Page output:
Copy codeThe Code is as follows:
String 'test' (length = 4)
Invoke