http://php.net/manual/zh/language.oop5.basic.php
1. class
class contain contants(常量) variables(变量or属性) and function(方法)
<?php class SimpleClass { // property declaration public $var = ‘a default value‘; // method declaration public function displayVar() { echo $this->var; } } ?>
pseudo-variable(伪变量) $this is a reference to the calling object
2. $this example
<?php class A { function foo() { if (isset($this)) { echo ‘$this is defined (‘; echo get_class($this); echo ")\n"; } else { echo "\$this is not defined.\n"; } } } class B { function bar() { // Note: the next line will issue a warning if E_STRICT is enabled. A::foo(); } } $a = new A(); $a->foo(); // Note: the next line will issue a warning if E_STRICT is enabled. A::foo(); $b = new B(); $b->bar(); // Note: the next line will issue a warning if E_STRICT is enabled. B::bar(); ?>
the above example will output
$this is defined (A) $this is not defined. $this is defined (B) $this is not defined.
3. new
create an instance of a class
4. extends
It is not possible to extend multiple classes
It is possible to access the overridden methods or static properties by referencing them with parent::.
<?php class ExtendClass extends SimpleClass { // Redefine the parent method function displayVar() { echo "Extending class\n"; parent::displayVar(); } } $extended = new ExtendClass(); $extended->displayVar(); ?>
5. ::class
used for class name resolution(类名解析)
You can get a string containing the fully qualified name of the ClassName class by using ClassName::class.
<?php namespace NS { class ClassName { } B echo ClassName::class; } ?>
output
NS\ClassName
6.
原文：http://www.cnblogs.com/iMirror/p/4475905.html