Functions to access entities and components inside systems

* src/system.scm: get-key
                  get-component

* src/examples/making-systems.scm: access functions testing

diff --git a/src/examples/making-systems.scm b/src/examples/making-systems.scm
index 37097191fd5387e888b2752fc989d19f69c6eed7..0addc1bf122d1ca923bfc5b74ea3fb49cae7992b 100644 (file)
--- a/src/examples/making-systems.scm
+++ b/src/examples/making-systems.scm
@@ -22,14 +22,27 @@
 
 (define-component a x y)
 
+(define-system (s1)
+  (lambda (e)
+    (list (new-entity (make-a 1 2))
+         (new-entity (make-a 10 20)))))
+
+(define-system (s2 a)
+  (lambda (e)
+    (for-each
+     (lambda (e1)
+       (format #t "Key: ~a  Component: ~a~%" (get-key e1) (get-component 'a e1)))
+     e)
+    '()))
+
 (define (making-systems)
   (let ((entities '())
        (components '()))
-    (receive (e c) (((make-system () (lambda (e) (list (new-entity (make-a 1 2)) (new-entity (make-a 10 20))))) entities components))
+    (receive (e c) ((s1 entities components))
             (set! entities e)
             (set! components c))
     (format #t "Two new entities with a:~%~a~%~a~%~%" entities components)
 
-    (((make-system (a) (lambda (e) (display e) (newline) '())) entities components))))
+    ((s2 entities components))))
 
 (export making-systems)

diff --git a/src/system.scm b/src/system.scm
index 2a9365b708530d33e558b2d714d0cb142ce5e8be..587fc066c339a134e874ddfd4efa6f1718584bf4 100644 (file)
--- a/src/system.scm
+++ b/src/system.scm
@@ -225,3 +225,16 @@
        make-system
        join-systems
        threaded-systems)
+
+
+;;; Entities and components access inside systems
+
+(define (get-key entity)
+  (car entity))
+
+(define (get-component component-name entity)
+  (assoc-ref (cdr entity) component-name))
+
+
+(export get-key
+       get-component)