How can I call a function assigned to a class's static array?

Question

I am trying to add a function to a static variable in a class, and then call that function from elsewhere in my code.

This works:

<?php

class MyClass {
    static $myVar = [];
    static function set_myVar($function) {
        self::$myVar[] = $function;
    }
}

MyClass::set_myVar(function () { echo 'hello world!'; });
$t = MyClass::$myVar[0];
$t();

?>

However, this does not:

<?php

class MyClass {
    static $myVar = [];
    static function set_myVar($function) {
        self::$myVar[] = $function;
    }
}

MyClass::set_myVar(function () { echo 'hello world!'; });
MyClass::$myVar[0]();

?>

It results in the following error:

Notice: Undefined variable: myVar in C:\xampp\htdocs\public\index.php on line 11

Fatal error: Function name must be a string in C:\xampp\htdocs\public\index.php on line 11

Can anyone tell me why?

Answer 1

The PHP interpreter tries to evaluate $myVar[0]() before referencing the static array in your class.

You can test it if you place

$myVar = ["set_myVar"];

before your error and you get:

Warning: Missing argument 1 for MyClass::set_myVar()