;;;; wh-engine/systems.lisp
;;;; facilities for defining systems
(in-package wh-engine)

(defvar *system-registry* ()
  "Alist of defined systems.")

(defvar *world-systems* ()
  "List of installed systems.")

(defun register-system (name init-fun-symbol update-fun-symbol sdl-event-rules
                        &key dependencies)
  (push `(,name ,init-fun-symbol ,update-fun-symbol
                ,sdl-event-rules
                ,dependencies)
        *system-registry*))

(defun install-systems (&rest systems)
  (loop for system-name in systems
        for system = (assoc system-name *system-registry*)
        do (pushnew system *world-systems*)
           ;; install dependencies
           (apply #'install-systems (fifth system))))