Check for plugin requirements are met, deactivate and send up admin notice if not

plugin-dependency-check.php

<?php
/**
 * Checks for dependencies, if not present it deactivates the plugin and sends up an admin notices
 * 
 * Intended to be placed within a plugin singleton class, calling self::$instance->includes() or similar.
 * Could be adapted to be in a regular class or classless
 * 
 * @author Joshua David Nelson, josh@joshuadnelson.com
 * @see http://10up.com/blog/2012/wordpress-plug-in-self-deactivation/
 */

/**
 * Include required files and starts the plugin
 *
 * @access private
 * @since 1.0.0
 * @return void
 */
private function includes() {
	add_action( 'plugins_loaded', array( $this, 'plugins_loaded' ) );
}
 
public function plugins_loaded() {
	if ( ! self::is_supported() ) {
		add_action( 'admin_notices', array( $this, 'deactivate_admin_notice' ) );
		add_action( 'admin_init', array( $this, 'plugin_deactivate' ) );
	}
}

private function plugin_deactivate() {
	deactivate_plugins( plugin_basename( __FILE__ ) );
}

private static function is_supported() {
	// Check for required classes/plugins, for example GFCommon for Gravity Forms
	if( class_exists( 'GFCommon' ) ) {
		return true;
	}
	return false;
}

/**
 *  Output admin notices
 */
public function deactivate_admin_notice( $message = '', $class = 'error' ) {
	if( empty( $message ) ) {
		$message = __( 'Plugin has been deactived. It requires Gravity Forms', 'text-domain' );
	}
	echo '<div class="' . $class . '"><p>' . $message . '</p></div>';
	
	// Removes "plugin activated" message
	if ( isset( $_GET['activate'] ) )
		unset( $_GET['activate'] );
}