PHP magic method application example code summary
This article mainly introduces a concise summary of Magic 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 specific namespace will 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 parameter array of the called method.
class MethodTest
{
public function call($name, $arguments)
{
// Note: value of $name is case sensitive.
echo "Calling object method '$name' "
. implode(' ', $arguments). "<br>";
}
public static function callStatic($name, $arguments)
{
// Note: value of $name is case sensitive.
echo "Calling static method '$name' "
. implode(' ', $arguments). "<br>";
}
}
$obj = new MethodTest;
$obj->runTest('in','object','context');
MethodTest::runTest('in','static','context');Among them, $arguments is passed in as an array. Running results:
Calling object method 'runTest' in object context
Calling static method 'runTest' in static context
Also pay attention to the scope protected and private of the function:
class TestMagicCallMethod {
public function foo()
{
echo METHOD.PHP_EOL."<br>";
}
public function call($method, $args)
{
echo METHOD.PHP_EOL."<br>";
if(method_exists($this, $method))
{
$this->$method();
}
}
protected function bar()
{
echo METHOD.PHP_EOL."<br>";
}
private function baz()
{
echo METHOD.PHP_EOL."<br>";
}
}
$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."<br>";
$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!
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