reference appendices

Extension Categorisation

PHP functionality is grouped into extensions. Some extensions are enabled by default, some are bundled but optional, and others require separate installation. A missing extension is a deployment concern, not an application mystery.

Use This Reference When

Declaring platform requirements in Composer.
Diagnosing “undefined function” or missing-class errors.
Preparing a production runtime or container image.

Composer Platform Requirements

{
  "require": {
    "php": "^8.5",
    "ext-json": "*",
    "ext-pdo": "*"
  }
}

Use php -m, php --ri extension, and Composer platform checks. Avoid assuming a local extension exists in production.

Practice

Declare an Extension Requirement

Add a required extension to a sample Composer manifest and describe how to confirm it exists in the runtime.

Show solution

Declare an ext-name package requirement and inspect php -m or php --ri name. Composer can then fail early when the platform is incomplete.