PHP 7.2 Function create_function() is deprecated

I have used create_function in my application below.

$callbacks[$delimiter] = create_function('$matches', "return '$delimiter' . strtolower(\$matches[1]);");

But for PHP 7.2.0, the create_function() is deprecated.

How to fix my code above on PHP 7.2.0.

Solution 1:

You should be able to use an Anonymous Function (aka Closure) with a call to the parent scoped $delimiter variable, like so:

$callbacks[$delimiter] = function($matches) use ($delimiter) {
    return $delimiter . strtolower($matches[1]);
};

Solution 2:

I would like to contribute with a very simple case I found in a Wordpress Theme and seems to work properly:

Having the following add_filter statement:

add_filter( 'option_page_capability_' . ot_options_id(), create_function( '$caps', "return '$caps';" ), 999 );

Replace it for:

add_filter( 'option_page_capability_' . ot_options_id(), function($caps) {return $caps;},999);

We can see the usage of function(), very typical function creation instead of a deprecated create_function() to create functions. Hope it helps.

Solution 3:

Automated Upgrade

If anyone needs to upgrade dozens of create_function() cases in their code to anonymous functions, I work on a tool called Rector.

It goes through the code and replaces the create_function with anonymous functions 1:1. It's tested on 30 various cases.

Install

composer require rector/rector --dev

Setup

Let's say you want to upgrade code in the /src directory.

# rector.php
<?php

use Rector\Core\Configuration\Option;
use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
use Rector\Php72\Rector\FuncCall\CreateFunctionToAnonymousFunctionRector;

return static function (ContainerConfigurator $containerConfigurator) {
    $parameters = $containerConfigurator->parameters();
    $parameters->set(Option::PATHS, [
        __DIR__ . '/src',
    ]);

    $services = $containerConfigurator->services();
    $services->set(CreateFunctionToAnonymousFunctionRector::class);
};

Run on your code

# this is set run, it only report what it would change
vendor/bin/rector process --config rector.php --dry-run

# this actually changes the code
vendor/bin/rector process --config rector.php

# the "rector.php" config is loaded by default, so we can drop it
vendor/bin/rector process

EDIT: Updated 2020-10-31 with PHP Rector 0.8.x syntax