Merge branch 'enums'

enums/Days.Mod

@@ -0,0 +1,68 @@
+MODULE Days;
+
+ TYPE 
+   Day* = POINTER TO DayDesc;
+   DayDesc = RECORD
+   next, prev : Day
+   END;
+   Week = ARRAY 7 OF Day;
+
+ VAR 
+   sun*, mon*, tue*, wed*, thu*, fri*, sat* : Day;
+   week: Week;
+
+ PROCEDURE Next*(d : Day): Day;
+ BEGIN
+   RETURN d.next
+ END Next;
+
+ PROCEDURE Prev*(d: Day): Day;
+ BEGIN
+   RETURN d.prev;
+ END Prev;
+
+ PROCEDURE inc(VAR j: SHORTINT);
+ BEGIN
+   IF j = 6 THEN
+     j := 0
+   ELSE
+     INC(j)
+   END
+ END inc;
+
+  PROCEDURE dec(VAR j: SHORTINT);
+ BEGIN
+   IF j = 0 THEN
+     j := 6
+   ELSE
+     DEC(j)
+   END
+ END dec;
+
+ PROCEDURE init(VAR w : Week);
+   VAR
+     i,j : SHORTINT;
+ BEGIN
+     i := 0;
+     REPEAT
+       j := i; inc(j);
+       w[i].next := w[j];
+       j := i; dec(j);
+       w[i].prev := w[j];
+       INC(i)
+     UNTIL i > 6;
+ END init;
+
+BEGIN
+  NEW(sun); NEW(mon); NEW(tue); NEW(wed); NEW(thu); NEW(fri); NEW(sat);
+  week[0] := sun;
+  week[1] := mon;
+  week[2] := tue;
+  week[3] := wed;
+  week[4] := thu;
+  week[5] := fri;
+  week[6] := sat;
+  
+  init(week);
+
+END Days.

enums/readme.md

@@ -0,0 +1,6 @@
+
+
+Example aimed to show how to survive without enumerations in Oberon.
+
+This way is even cooler than enumerations. (:
+

enums/test.Mod

@@ -0,0 +1,22 @@
+MODULE test;
+
+IMPORT Days, Out;
+
+VAR today, yesterday, tomorrow: Days.Day;
+
+BEGIN
+  today := Days.mon; (*init*)
+
+  yesterday := Days.Prev(today);
+  IF yesterday = Days.sun
+  THEN
+    Out.String("it works!"); Out.Ln
+  END;
+  tomorrow := Days.Next(today);
+
+  IF tomorrow = Days.tue
+  THEN
+    Out.String("it works!"); Out.Ln
+  END;
+
+END test.