actors: Permit docstrings in mlambda.

[8sync.git] / 8sync / systems / actors.scm

diff --git a/8sync/systems/actors.scm b/8sync/systems/actors.scm
index c33240f309cc181dcf030b905a43b989e4cec186..c75a25aaa5de0421f775c834d82a306048295077 100644 (file)
--- a/8sync/systems/actors.scm
+++ b/8sync/systems/actors.scm
@@ -48,7 +48,7 @@
             actor-id-string
 
             mlambda define-mhandler
-            make-action-dispatch
+            simple-dispatcher build-actions make-action-dispatch
             define-simple-actor
 
             <hive>
@@ -323,7 +323,7 @@ If key not found and DFLT not provided, throw an error."
     body body* ...))
 
 (define-syntax mlambda
-  (syntax-rules ()
+  (lambda (x)
     "A lambda for building message handlers.
 
 Use it like:
@@ -334,13 +334,19 @@ Which is like doing manually:
   (lambda (actor message)
     (let ((foo (message-ref message foo)))
       ...))"
-    ((_ (actor message message-arg ...)
-        body body* ...)
-     (lambda (actor message)
-       (with-message-args (message message-arg ...) body body* ...)))))
+    (syntax-case x ()
+      ((_ (actor message message-arg ...)
+          docstring
+          body ...)
+       (string? (syntax->datum #'docstring))
+       #'(lambda (actor message)
+           docstring
+           (with-message-args (message message-arg ...) body ...)))
+      ((_ (actor message message-arg ...)
+          body body* ...)
+       #'(lambda (actor message)
+           (with-message-args (message message-arg ...) body body* ...))))))
 
-;; @@: Sadly, docstrings won't work with this...
-;;   I think we need to bust out syntax-case to make that happen...
 (define-syntax-rule (define-mhandler (name actor message message-arg ...)
                       body ...)
   (define name
@@ -352,6 +358,8 @@ Which is like doing manually:
     (let* ((action (message-action message))
            (method (assoc-ref action-map action)))
       (if (not method)
+          ;; @@: There's every possibility this should be handled in
+          ;;  hive-process-message instead.
           (throw 'action-not-found
                  "No appropriate action handler found for actor"
                  #:action action
@@ -370,6 +378,12 @@ Which is like doing manually:
      (cons (quote action-name) handler))))
 
 (define-syntax-rule (build-actions action-item ...)
+  "Build a mapping of actions.  Same syntax as make-action-dispatch
+but this doesn't build the dispatcher for you (you probably want to
+pass it to simple-dispatcher).
+
+The advantage here is that since this simply builds an alist, you can
+compose it with other action maps."
   (list (%expand-action-item action-item) ...))
 
 (define-syntax make-action-dispatch