Framework for declaring and resolving plugin dependencies in WordPress.

Since: 6.5.0
Source: wp-includes/class-wp-plugin-dependencies.php

Components

Declaring Dependencies

Plugins declare dependencies via the Requires Plugins header:

/**
 * Plugin Name: My Plugin
 * Requires Plugins: woocommerce, jetpack
 */

Dependencies are listed as comma-separated slugs matching WordPress.org format.

Initialization Flow

plugins_loaded
    └── WP_Plugin_Dependencies::initialize()
            ├── read_dependencies_from_plugin_headers()
            │       ├── Parse 'Requires Plugins' headers
            │       ├── Sanitize slugs via wp_plugin_dependencies_slug filter
            │       └── Build dependency/dependent maps
            └── get_dependency_api_data()
                    └── Fetch plugin info from WordPress.org API

Dependency Resolution

Plugin Activation Check
    ├── has_dependencies( $plugin_file )
    │       └── Does plugin require other plugins?
    ├── has_unmet_dependencies( $plugin_file )
    │       └── Are any dependencies missing/inactive?
    ├── has_circular_dependency( $plugin_file )
    │       └── Detect A→B→A loops
    └── get_dependency_filepath( $slug )
            └── Find installed dependency location

Key Concepts

Admin Integration

The class displays admin notices for:

• Unmet dependencies (missing or inactive required plugins)
• Circular dependencies (plugins that depend on each other)

AJAX handler validates dependencies after plugin installation.