Question

I’m trying to make an associative array with values that are references to functions. What is the proper way to do this? This code works, but gives me a warning.

Code

<?php

$mergeCodes = array(
    'rev:(\d+)' => reverse_me,
);

$test = "This is a [[rev:1234]] test";

echo "BEFORE: $test\n";
foreach ($mergeCodes as $code => $callback) {
    $code = '\[\[' . $code . '\]\]';
    $test = preg_replace_callback( "/$code/", $callback, $test );
}
echo "AFTER: $test\n";

function reverse_me($input) {
    return strrev($input[1]);
}

?>

Output

PHP Notice:  Use of undefined constant reverse_me - assumed 'reverse_me' in /tmp/test2.php on line 4
BEFORE: This is a [[rev:1234]] test
AFTER: This is a 4321 test

Answer 1

As far as I know, PHP does not have such concept. You’re probably confused by JavaScript.

It seems that your final purpose is to make a call to preg_replace_callback(). As the name suggests you have to feed it with a callback and that’s something pretty simple. All you need is a regular variable that contains one of these:

• A string with a variable name: 'foo'
• An array with a class name and a method name: array('Foo', 'doBar')
• An array with a class instance and a method name: array($myFoo, 'doBar')

Find further reference at https://www.php.net/manual/en/language.types.callable.php