SandwichInterface.php

<?php

namespace Drupal\plugin_type_example;


/**
 * An interface for all Sandwich type plugins.
 *
 * When defining a new plugin type you need to define an interface that all
 * plugins of the new type will implement. This ensures that consumers of the
 * plugin type have a consistent way of accessing the plugin's functionality. It
 * should include access to any public properties, and methods for accomplishing
 * whatever business logic anyone accessing the plugin might want to use.
 *
 * For example, an image manipulation plugin might have a "process" method that
 * takes a known input, probably an image file, and returns the processed
 * version of the file.
 *
 * In our case we'll define methods for accessing the human readable description
 * of a sandwich and the number of calories per serving. As well as a method for
 * ordering a sandwich.
 */
interface SandwichInterface {
    
    /**
     * Provide a description of the sandwich.
     *
     * @return string
     *   A string description of the sandwich.
     */
    public function description();
    
    /**
     * Provide the number of calories per serving for the sandwich.
     *
     * @return float
     *   The number of calories per serving.
     */
    public function calories();
    
    /**
     * Place an order for a sandwich.
     *
     * This is just an example method on our plugin that we can call to get
     * something back.
     *
     * @param array $extras
     *   An array of extra ingredients to include with this sandwich.
     *
     * @return string
     *   Description of the sandwich that was just ordered.
     */
    public function order(array $extras);

}