Access public static variable inside class in function php

Question

I am trying to access a variable within a class in a function:

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 }

outside: google_api_v3::$api_key should also work? and inside use: self::$api_key or static::$api_key — Raphael Müller
– Raphael Müller, Commented Sep 4, 2014 at 9:18
@user3467855 Btw, since you seem to think it's about variable visibility, the fact that your variable is public or private has nothing to do with your problem. I don't get how "it works only on private" with $this->api_key, it shouldn't work. — Clément Malet
– Clément Malet, Commented Sep 4, 2014 at 9:42

Clément Malet · Accepted Answer · 2014-09-05 07:17:07Z

10

A generic way to use values / methods (including static ones) inside the class is self::

echo self::$api_key;

edited Sep 5, 2014 at 7:17

answered Sep 4, 2014 at 9:20

Clément Malet

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3 Comments

Robert Over a year ago

self enforces use of current class only when you extend class and you override static variable it will show strange results. That is why it's much better to use static keyword or just point the class name from which u want to get static variable.

Clément Malet Over a year ago

@Robert At the moment where I wrote the answer, all the given / hinted solutions were 'ClassName::field', I just wanted to give another solution. I could have insisted more on the generic word, but your answer is doing the job, great.

Robert Over a year ago

yep :) but using self can be tricky sometimes :P for example in Singleton when you use traits static:: is the only solution which will be flexible

Robert · Accepted Answer · 2014-09-04 09:58:21Z

There are many ways to do it no one mentioned about static keyword

you can do inside class:

static::$api_key

You can also use references and keywords like parent, self or using class name.

There is difference between self and static. When you override static variable in class self:: will point to the class where it was called and static:: does is wiser and will check ovverides. There's example from php.net side written in comments I've modifed it a bit just to show differences.

<?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();

Output:

class b class a class a class b

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