From bed3604685f7783503c718fc9116be89953bc33c Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Thu, 23 May 2024 16:33:45 -0400
Subject: [PATCH] Adjust emitters to not produce side-effects in 'wire-state'
 method.

---
 modules/game/actors.scm | 40 +++++++++++++++++++---------------------
 1 file changed, 19 insertions(+), 21 deletions(-)

diff --git a/modules/game/actors.scm b/modules/game/actors.scm
index 07d507e..43ee1f9 100644
--- a/modules/game/actors.scm
+++ b/modules/game/actors.scm
@@ -127,20 +127,19 @@
   (match-lambda*
     (('type) 'emitter)
     (('position) position)
-    (('tick grid-info) ($ timer (+ ($ timer) 1)))
+    (('tick grid-info)
+     (let ((t (modulo (+ ($ timer) 1) interval)))
+       ($ timer t)
+       (when (= t 0)
+         ($ grid-info 'append-event `(emit ,x ,y)))))
     (('post-tick grid-info) #f)
     (('enter obj grid-info) #f)
     (('exit obj grid-info) #f)
     (('wire-state grid-info)
-     (let ((t ($ timer)))
-       (cond
-        ((= (modulo t interval) 0)
-         ($ grid-info 'append-event `(emit ,x ,y))
-         'electron-head)
-        ((= (modulo t interval) 1)
-         'electron-tail)
-        (else
-         'copper))))
+     (match ($ timer)
+       (0 'electron-head)
+       (1 'electron-tail)
+       (_ 'copper)))
     (('update-wire-state grid-info) #f)
     (('alive?) #t)
     (('describe) `(clock-emitter ,position))
@@ -155,27 +154,26 @@
     (('position) position)
     (('tick grid-info)
      (when ($ on?)
-       ($ timer (+ ($ timer) 1))))
+       (let ((t (modulo (+ ($ timer) 1) interval)))
+         ($ timer t)
+         (when (= t 0)
+           ($ grid-info 'append-event `(emit ,x ,y))))))
     (('post-tick grid-info) #f)
     (('enter obj grid-info) #f)
     (('exit obj grid-info) #f)
     (('activate grid-info)
      ($ on? #t)
-     ($ timer 0)
+     ($ timer -1)
      ($ grid-info 'append-event `(emitter-on ,x ,y)))
     (('deactivate grid-info)
      ($ on? #f)
      ($ grid-info 'append-event `(emitter-off ,x ,y)))
     (('wire-state grid-info)
-     (when ($ on?)
-       (let ((t ($ timer)))
-         (cond
-          ((= (modulo t interval) 0)
-           'electron-head)
-          ((= (modulo t interval) 1)
-           'electron-tail)
-          (else
-           'copper)))))
+     (and ($ on?)
+          (match ($ timer)
+            (0 'electron-head)
+            (1 'electron-tail)
+            (_ 'copper))))
     (('update-wire-state grid-info) #f)
     (('alive?) #t)
     (('on?) ($ on?))