You don't necessarily need Composer

Don’t get me wrong, Composer is an amazing product. It has an easy-to-use API for quick autoloading, supports multiple standards, and has autoloading optimization built-in - it even lets you search and require packages easily. It’s a reason Composer is the most used package manager for PHP.

If your project is a lightweight OOP project with no external packages though. Using Composer might be a bit overkill, you could easily implement autoloading using a simple array and PHP’s spl_autoload_register function.

For those not familiar, spl_autoload_register is what we can use to add to our own autoloading function to PHPs autoloading queue. We can use that together with a simple array $classmap to autoload our small project. Here’s our project structure.

  • /public/index.php
  • /src/**/*.php
  • autoload.php

/public will be our front-facing entry point, /src will hold our classes, and autoload.php will handle our autoloading. Our classes will be formatted in PSR-4, with our vendor namespace prefix being used as the key for our internal $classmap.

Let’s create our autoload.php file and add some autoloading to our project.

define('PHPNEXUS_VERSION', '0.0.1');

$classmap = [
    'PHPNexus' => __DIR__ . '/src/',
];

spl_autoload_register(function(string $classname) use ($classmap) {
    $parts = explode('\\', $classname);

    $namespace = array_shift($parts);
    $classfile = array_pop($parts) . '.php';

    if (! array_key_exists($namespace, $classmap)) {
        return;
    }

    $path = implode(DIRECTORY_SEPARATOR, $parts);
    $file = $classmap[$namespace] . $path . DIRECTORY_SEPARATOR . $classfile;

    if (! file_exists($file) && ! class_exists($classname)) {
        return;
    }

    require_once $file;
});

Going over our code shows we first define a new constant - PHPNEXUS_VERSION, this will be used to check if our autoload file has already been loaded later. $classmap is an associative array - as previously mentioned our vendor namespace is our key. The value of which is the location to our source files, in this case, that is /src. And since autoloading.php is in our root, we can take advantage of the __DIR__ constant.

The first argument of spl_autoload_register is the callback function - that’s our autoloading function. That function will take a string parameter - when you instantiate a class with new, the FQCN gets passed as that parameter’s argument.

Next, we are destructuring our $classname argument by separating each value into an array $parts variable. Since we know our first $parts value is our vendor namespace, we use array_shift to grab it and use array_pop to grab the actual filename since we also know that’s the last part of our $classname.

We then do a quick check to see if the $namespace is in our $classmap so we can handle the file location, if that’s not the case we simply do an early return out of the function.

$path will be the variable holding the remaining parts of our $parts array, since the filename and namespace are already removed, we can assume the rest of the pieces are the rest of our file path.

We then reassemble our file path info into a temporary $file variable and check if that file exists. As a precaution, we also include a check to see if the class has already been defined. If either fails - as before, we return out of the function and be on our merry way.

Lastly, if nothing fails all we do is require the $file that contains our class so PHP can now initialize it.

To then use our simple autoloading file, in our public/index.php we simply add the following if statement.

if (! defined('PHPNEXUS_VERSION')) {
    require_once dirname(__DIR__) . '/autoload.php';
}

This does a check for the earlier constant to see if the file has already been included or required earlier, if that fails we require our autoload.php file and now we can use our classes, e.g. if we had a PHPNexus\Request\Request class located in /src/Request/Request.

if (! defined('PHPNEXUS_VERSION')) {
    require_once dirname(__DIR__) . '/autoload.php';
}

use PHPNexus\Request\Request;

$request = new Request($_SERVER);

And that’s how we can create simple autoloading for our project without having to rely on Composer. As mentioned above though, if your project already requires packages from other sources via Composer, then it’s best to stick with Composers autoloader instead.

To leave off, have you ever written your own function to handle autoloading before? Perhaps you didn’t know how to do it and you know do, let me know by replying to the topic. Would love to hear your thought on implementing simple autoloading for projects.

2 Likes

Interesting read, it is always good to understand how autoloading works under the hood. I had to do something custom for Polyel, the PHP framework that I built based on Swoole, autoloading and preloading all files at server startup, I even implemented preloading all Composer packages as well so a project does not need to perform any classmap lookups, which can be a huge performance hit if your classmap is in the thousands.

You can read more about Composer package preloading in Polyel here if you are interested :slightly_smiling_face: But Polyel also preloads all of your application files as well at server startup, very different from traditional PHP.

1 Like

Haven’t looked into preloading, could be a fun exercise to implement one day. Though I’d stick with a simple classmap lookup for a simple autoloader - the simplicity would outway any performance gain, especially for smaller projects that just needs to load a few classes under a single namespace. That is unless performance is a key metric for that project.

I’m thinking like a plugin with a single namespace, no external dependencies, a perfect use-case for a classmap autoloader I believe. In that case, though, the classmap table could be hardcoded into the autoloader itself instead of using the array lookup.

It’s fun to see that there are so many different ways to implement a single feature such as autoloading. Interested to see what more I can learn on the subject so I’ll check out how Polyel does it later today. :+1:

1 Like