1 files changed, 25 insertions, 6 deletions
diff --git a/starling/asset.scm b/starling/asset.scm
index c1a05a1..8ddf945 100644
--- a/starling/asset.scm
+++ b/starling/asset.scm
@@ -32,7 +32,10 @@
             artifact
             file-name
             loader
-            args
+            loader-args
+            on-asset-reload
+            add-subscriber
+            remove-subscriber
             watch-assets
             watching-assets?
             watch-asset-directory
@@ -57,7 +60,8 @@
   (file-name #:getter file-name #:init-keyword #:file-name)
   (loader #:getter loader #:init-keyword #:loader)
   (loader-args #:getter loader-args #:init-form '()
-               #:init-keyword #:loader-args))
+               #:init-keyword #:loader-args)
+  (subscribers #:getter subscribers #:init-form (make-weak-key-hash-table)))
 
 (define (absolute-file-name file-name)
   (if (absolute-file-name? file-name)
@@ -80,6 +84,23 @@
                           wt))))
     (hash-set! sub-table asset asset)))
 
+(define-method (on-asset-reload obj slot-name)
+  #t)
+
+(define-method (add-subscriber (asset <asset>) obj slot-name)
+  (let ((subs (subscribers asset)))
+    (hashq-set! subs obj (cons slot-name (hashq-ref subs obj '())))))
+
+(define-method (remove-subscriber (asset <asset>) obj slot-name)
+  (let* ((subs (subscribers asset))
+         (slot-names (delq slot-name (hashq-ref subs obj '()))))
+    (if (null? slot-names)
+        (hashq-remove! subs obj)
+        (hashq-set! subs obj slot-names))))
+
+(define-method (notify-subscribers (asset <asset>))
+  (hash-for-each on-asset-reload (subscribers asset)))
+
 (define-method (asset-purge (asset <asset>))
   (hash-remove! (hash-ref (asset-file-map) (file-name asset)) asset))
 
@@ -151,7 +172,8 @@
                              (expire-cached-artifact (cache-key asset)))
                            assets)
             (hash-for-each (lambda (key asset)
-                             (load! asset))
+                             (load! asset)
+                             (notify-subscribers asset))
                            assets))))))))
 
 (define (cache-key asset)
@@ -192,9 +214,6 @@
   (or (hashq-ref (asset-artifact-map) asset)
       (load! asset #t)))
 
-;; Make assets that are outside of the cache "just work".
-(define-method (asset-ref x) x)
-
 ;; Handy syntax for defining new assets.
 (define-syntax-rule (define-asset name
                       (loader file-name loader-args ...))