PHP magic method application example code summary

This article mainly introduces a concise summary ofMagic Method(Magic Method) in PHP classes. These methods include construct(), destruct(), call(), callStatic(), get() , set(), toString(), etc. Friends who need it can refer to

1. construct() and destruct()

when the instance is created/destroyed When called, zero or more parameters can be passed.

class A { function A() { echo "build A"; } function destruct() { echo "destroy A"; } } $obj = new A(); //unset($obj);

Note：The destructor method will be called as soon as there are no other references to a particular object, or in any order during the shutdown sequence.

　AboutConstructor, starting from PHP5.3.3, a method named with the class name in a class defined in a specificnamespacewill no longer be considered a constructor. In a class without a namespace, it is still a constructor as before. For example:

namespace Foo; class Bar { public function Bar() { // treated as constructor in PHP 5.3.0-5.3.2 // treated as regular method as of PHP 5.3.3 } }

If there is no namespace Foo; then Bar() will also be used as a constructor. In addition, if the following situation exists:

function construct() { echo "construct A"; } function A() { echo "build A"; } function destruct() { echo "destroy A"; } }

contains both construct() and a function with the same name as the class name, then only construct() will be called.

2. call() and callStatic()

Called when trying to call a method that does not exist. Two parameters, one is the method name, and the other is the parameterarrayof the called method.

class MethodTest { public function call($name, $arguments) { // Note: value of $name is case sensitive. echo "Calling object method '$name' " . implode(' ', $arguments). "
"; } public static function callStatic($name, $arguments) { // Note: value of $name is case sensitive. echo "Calling static method '$name' " . implode(' ', $arguments). "
"; } } $obj = new MethodTest; $obj->runTest('in','object','context'); MethodTest::runTest('in','static','context');

Among them, $arguments is passed in as an array. Running results:

Calling object method 'runTest' in object context
Calling static method 'runTest' in static context

Also pay attention to the scope protected and private of the function:

class TestMagicCallMethod { public function foo() { echo METHOD.PHP_EOL."
"; } public function call($method, $args) { echo METHOD.PHP_EOL."
"; if(method_exists($this, $method)) { $this->$method(); } } protected function bar() { echo METHOD.PHP_EOL."
"; } private function baz() { echo METHOD.PHP_EOL."
"; } } $test = new TestMagicCallMethod(); $test->foo(); /** * Outputs: * TestMagicCallMethod::foo */ $test->bar(); /** * Outputs: * TestMagicCallMethod::call * TestMagicCallMethod::bar */ $test->baz(); /** * Outputs: * TestMagicCallMethod::call * TestMagicCallMethod::baz */

3.get() and set()

are called when trying to read properties of an object that do not exist.

Note: We can use this function to implement various operations similar to reflection in java.

class Test { public function get($key) { echo $key . " not exists"; } public function set($key,$value) { echo $key . " = ".$value; } } $t = new Test(); echo $t->name."
"; $t->name = "abc";

Output:
name not exists
name = abc

4. toString()

This method is similar to java toString() method, this function is called when we print the object directly. The function must return a string.

class Test { private $name = "abc"; private $age = 12; public function toString() { return "name : $this->name, age : $this->age"; } } $t = new Test(); echo $t;

Output:

name : abc, age : 12

The above is the detailed content of PHP magic method application example code summary. For more information, please follow other related articles on the PHP Chinese website!