Access Static properties using PHP object

问题

This is with reference to Get a static property of an instance, I am a newbie and have the following code :

class Foo
{
   public static $my_static = 1;
}

class Bar extends Foo
{

}

$foo = new Foo();
$boo = new Bar();

echo Foo::$my_static;  // ok
echo Bar::$my_static;  // ok
echo $foo::$my_static; // ok
echo $boo::$my_static; // ok

Static variables/properties are accessed only as ClassName::static_property as in C++, but it is not the case in PHP... but PHP books mostly mention the className::static_property pattern, not the object::static_property construct. Need more light on this..

回答1:

Static properties may be accessed on various ways.

Class::$aStaticProp; //by class name

$classname::$aStaticProp; // As of PHP 5.3.0 by object instance

Static properties cannot be accessed through the object using the arrow operator ->.

As of PHP 5.3.0, it's possible to reference the class using a variable. The variable's value can not be a keyword (e.g. self, parent and static).

回答2:

$instance::$staticProperty is simply a convenience shorthand for Class::$staticProperty. Since you already have an instance of a class and the syntax is unambiguous, PHP saves you from writing a potentially long class name. There's no functional difference.

回答3:

within the class you have to use like self::$staticPropery if the function accessing to the variable is also static.

来源：https://stackoverflow.com/questions/17107869/access-static-properties-using-php-object

标签

php

static