Implementing Basic Caching in PHP

A basic cache stores computed results with expiration to reduce repeated work.

What It Does

A basic cache stores computed results with expiration to reduce repeated work. 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
$cache = [];
$key = 'product:4';
$cache[$key] = ['value' => 17, 'expires' => time() + 60];
echo $cache[$key]['value'];

Example 2: Another Case

Check failure behavior or a different execution path.

<?php
$ttl = 30; $savedAt = time() - 40;
var_dump(time() < $savedAt + $ttl);

Practical Example: Putting It to Use

In-request memoization is distinct from cross-request APCu/Redis caching.

<?php
$cache = [];
function loadProduct(array &$cache, string $id): string { return $cache[$id] ??= 'Product-' . $id; }
echo loadProduct($cache, 'p7');

Important Behavior and Edge Cases

Choose clear cache keys, bounds and invalidation rules; local arrays do not persist between PHP-FPM requests.

Comparison with Related Functions or Approaches

Common Beginner Mistakes

Key Takeaways

• A basic cache stores computed results with expiration to reduce repeated work.
• Choose clear cache keys, bounds and invalidation rules; local arrays do not persist between PHP-FPM requests.
• Use APCu or Redis for caching beyond a single request.

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