PHP Version Check

gistfile1.php

<?php

class MyPlugin {
	
	/** 
 	* Add this at top of your plugin class constructor or whichever method in your class you use to bootstrap your plugin.
 	* e.g. public static function bootstrap()
 	*/
 	public static function bootstrap() {
 		if ( version_compare( '5.3', phpversion(), '>' ) ) {
			add_action( 'admin_notices', array( __CLASS__, 'php_version_notice' ) );
			return; // Exit method before doing other cool things
		}
 	}

	/**
	 * Hooks `admin_notices`. Must echo to be useful.
	 */
	public static function php_version_notice( $echo = true ) {
		$content = '<div class="error"><p>' . esc_html__( 'MYPLUGIN is not active because your server is not running at least PHP version 5.3. Please update or contact your server administrator.', 'textdomain' ) . '</p></div>';
		if ( $echo )
			echo $content;
		return $content;
	}
}