Question

If I have code which uses a static variable for caching purposes like this:

class BossParty
{
    // ...

    public function getTemplate()
    {
        static $template;

        if ($template == null)
        {
            $template = BossTemplate::get($this->templateID);
        }

        return $template;
    }

    // ...
}

Will $template persist across different instances of BossParty? I’ve tried checking php.net, but all I can find is info about static class variables.

Answer 1

Yes, the static variable will persist across instances of the class.

Example:

<?php

class Test {
    public function __construct() {
        static $foo;

        if ($foo) {
            echo 'found';
        } else {
            $foo = 'foobar';
        }
    }
}

$test1 = new Test();
$test2 = new Test();
// output "found"

---

Note that this is true for descendant classes too. If we had a class Child that extended Test, calling parent::__construct (whether explicitly or implicitly) will use the same value of $foo.