Applying the Factory Pattern in PHP

A factory centralizes which concrete object to construct for a requested mode or configuration.

What It Does

A factory centralizes which concrete object to construct for a requested mode or configuration. The following examples distinguish a normal use case, a boundary case and a practical application.

Requirements and Compatibility

PHP 8.x and a local test environment. Apply input validation, correct error handling and the requirements of any optional libraries.

The code focuses on the core concept. Production implementation may also need routes, validation, persistence, authorization or deployment tooling.

Example 1: Basic Behavior

Understand the primary operation and its inputs.

<?php
interface Exporter { public function type(): string; }
class CsvExporter implements Exporter { public function type(): string { return 'csv'; } }
function exporter(string $format): Exporter { return match ($format) { 'csv' => new CsvExporter(), default => throw new InvalidArgumentException('Unknown format') }; }
echo exporter('csv')->type();

Example 2: Another Case

Check failure behavior or a different execution path.

<?php
class CacheService { public function __construct(public string $name) {} }
$container = ['cache' => fn () => new CacheService('local')];
$cache = $container['cache']();
echo $cache->name;

Practical Example: Putting It to Use

Apply the behavior in a small, controlled scenario.

<?php
interface QueuePort { public function name(): string; }
class MemoryQueue implements QueuePort { public function name(): string { return 'memory'; } }
function queueFactory(bool $testMode): QueuePort { if ($testMode) return new MemoryQueue(); throw new RuntimeException('Configure production queue'); }
echo queueFactory(true)->name();

Important Behavior and Edge Cases

Do not build an opaque global service locator to avoid simple constructor injection.

Comparison with Related Functions or Approaches

Common Beginner Mistakes

Key Takeaways

• A factory centralizes which concrete object to construct for a requested mode or configuration.
• Do not build an opaque global service locator to avoid simple constructor injection.
• A service container manages object construction across larger dependency graphs.

Before adapting these examples, verify the return values, test the failure paths and confirm that your application meets its security and environment requirements.