From 6099125a86c37ae12c48eeb88127c9ccc29fffab Mon Sep 17 00:00:00 2001
From: Jay McCarthy <jay.mccarthy@gmail.com>
Date: Tue, 14 Apr 2015 14:00:59 -0400
Subject: [PATCH] add word-evt

---
 scribblings/lux.scrbl | 5 +++++
 word.rkt              | 6 +++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/scribblings/lux.scrbl b/scribblings/lux.scrbl
index 0e37587..fc6d1d4 100644
--- a/scribblings/lux.scrbl
+++ b/scribblings/lux.scrbl
@@ -72,6 +72,11 @@ Returns a label for @racket[w] that could use @racket[frame-time] to
 show the performance of the @tech{word} rendering. By default, returns
 @racket[(lux-standard-label "Lux" frame-time)].}
 
+@defproc[(word-evt [w word?]) evt?]{
+
+Returns a synchronizable event that the @tech{word} @racket[w]
+requires notification of. By default, returns @racket[never-evt].}
+
 @defproc[(word-event [w word?] [e any/c]) word?]{
 
 Returns a @tech{word} based on @racket[w] that integrates the
diff --git a/word.rkt b/word.rkt
index 2768cc7..0675787 100644
--- a/word.rkt
+++ b/word.rkt
@@ -10,6 +10,7 @@
 (define-generics word
   (word-fps word)
   (word-label word frame-time)
+  (word-evt word)
   (word-event word evt)
   (word-tick word)
   (word-output word)
@@ -19,6 +20,8 @@
      60.0)
    (define (word-label w frame-time)
      (lux-standard-label "Lux" frame-time))
+   (define (word-evt w)
+     never-evt)
    (define (word-event w e) w)
    (define (word-tick w) w)
    (define (word-output w) #f)
@@ -74,7 +77,8 @@
   (define (body next-time w)
     (define input-evt
       (handle-evt
-       (chaos-event c)
+       (choice-evt (word-evt w)
+                   (chaos-event c))
        (λ (e)
          (update-word w
                       (λ (w)