6. Classes & Autoloading — How Modern PHP Organizes Code

Why this matters

Modern PHP relies on:

AI often generates code that looks object‑oriented but violates these conventions.
Your mental model helps you see when something is out of place.

A class defines:

class User {
    public string $name;
    public function greet(): string {
        return "Hello, {$this->name}";
    }
}

Objects created from the class live only for the duration of the request
— there is no persistent memory unless you build it yourself.

Namespaces give structure:

namespace App\Models;
class User { ... }

They prevent:

AI sometimes invents namespaces that don’t exist.
Your mental model helps you catch that instantly.

Modern PHP uses PSR‑4 autoloading, which maps:

Example:

App\Models\User

maps to:

src/Models/User.php

If the structure doesn’t match, autoloading breaks
— and this is one of the most common AI‑generated errors..

PHP does not load every class at the start.
It loads a class the moment it is first referenced.

This keeps memory usage low and performance predictable
— a natural fit for PHP’s request‑driven model.

AI often mixes these incorrectly.
Our understanding helps us correct it.

Just like variables and functions:

…all disappear when the request ends.

There is no long‑running application memory unless you build it yourself
(using workers, caches, queues, or external services).

Modern PHP’s class model is:

- structured
- predictable
- filesystem‑driven
- namespace‑aware
- autoloaded on demand

Once we internalize this,
we can immediately see when AI‑generated code “feels wrong”
— even before we run it.