Finding Unused Dependencies in a PHP Project

Unused-package scans identify candidates for removal, followed by source and runtime checks.

What It Does and When to Use It

List direct requirements and explain a dependency chain. Direct PHP code exposes the underlying operation clearly; a framework can supply lifecycle hooks, dependency wiring and retries.

Requirements, Inputs and Expected Behavior

Confirm the runtime, extension, environment variables, and permissions before running the examples in production. Autoloaded plugins, CLI scripts and dynamic classes may be used without static references.

Example 1: Basic Operation

List direct requirements and explain a dependency chain.

composer show --direct
composer why psr/log

Example 2: Behavior and Validation

Audit vulnerable packages and identify stale direct dependencies.

composer audit --locked
composer outdated --direct

Practical Example: Application Use

List declared runtime packages; usage analysis also requires static and runtime inspection.

<?php
$composer=json_decode(file_get_contents(__DIR__.'/composer.json'),true,512,JSON_THROW_ON_ERROR);
foreach (array_keys($composer['require']??[]) as $package) echo $package,PHP_EOL;

Important Behavior and Edge Cases

The second example highlights: Audit vulnerable packages and identify stale direct dependencies. The practical example adds: List declared runtime packages; usage analysis also requires static and runtime inspection.

Comparison with Related Approaches

Approach	What changes
Direct operation versus framework-managed integration	Direct PHP code exposes the underlying operation clearly; a framework can supply lifecycle hooks, dependency wiring and retries.
Choosing safely	Choose based on deployment requirements and verify actual behavior rather than assuming defaults.

Common Beginner Mistakes

Mistake	Correct approach
Assuming successful execution proves the result is usable	Check the return value, required extension, and observable output of the specific operation.
Ignoring runtime and environment differences	Verify PHP version, SAPI, operating system, service access, and permissions before deployment.
Skipping operational constraints	Autoloaded plugins, CLI scripts and dynamic classes may be used without static references.

Key Takeaways

Unused-package scans identify candidates for removal, followed by source and runtime checks.
List declared runtime packages; usage analysis also requires static and runtime inspection.
Choose based on deployment requirements and verify actual behavior rather than assuming defaults.