[英]Cannot Access Global Variable inside function INSIDE public function PHP
[英]Access public static variable inside class in function php
我试图在函数中访问类中的变量:
class google_api_v3 {
public static $api_key = 'this is a string';
function send_response() {
// access here $api_key, I tried with $this->api_key, but that works only on private and that variable I need also to access it outside the class that is why I need it public.
}
}
function outside_class() {
$object = new google_api_v3;
// works accessing it with $object::api_key
}
使用值一个通用的方法/在类中的方法(包括静态的)是self::
echo self::$api_key;
class google_api_v3 {
public static $api_key = 'this is a string';
function send_response() {
$key = google_api_v3::$api_key
}
}
function outside_class() {
$object = new google_api_v3;
// works accessing it with $object::api_key
}
有很多方法可以做到没有人提到静态关键字
你可以在课堂上做:
static::$api_key
您还可以使用父,自我或使用类名等引用和关键字。
自我和静态之间存在差异。 当你在类中重写静态变量时,self ::将指向调用它的类,static :: does更加明智,并将检查ovverides。 有一些来自php.net的例子写在评论中我已经修改了一点只是为了显示差异。
<?php
abstract class a
{
static protected $test="class a";
public function static_test()
{
echo static::$test; // Results class b
echo self::$test; // Results class a
echo a::$test; // Results class a
echo b::$test; // Results class b
}
}
class b extends a
{
static protected $test="class b";
}
$obj = new b();
$obj->static_test();
输出:
class b
class a
class a
class b
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