More work on the NDA

abCalcNDA.c

@@ -240,6 +240,20 @@ void UpdateStack(void)
 }
 
 
+BOOLEAN ErrorRaised(void)
+{
+    char *errorString = abCalcGetError();
+    if (errorString == NULL) {
+        return FALSE;
+    }
+
+    AlertWindow(awCString+awResource, (Pointer)&errorString, abCalcErrorAlert);
+
+    abCalcClearError(); 
+    return TRUE;
+}
+
+
 void PushCalcEntry(CtlRecHndl entryBox)
 {
     static Str255 strBuf;
@@ -274,10 +288,13 @@ void ExecCalcCmd(char *cmd)
 
     PushCalcEntry(entryBox);
 
-    if (op != NULL) {
+    if ((!ErrorRaised()) &&
+        (op != NULL)) {
         op->execute();
     }
 
+    ErrorRaised();
+    
     UpdateStack();
 }
 
@@ -316,7 +333,13 @@ void HandleOpClick(void)
         if (op != NULL) {
             CtlRecHndl entryBox = GetCtlHandleFromID(gCalcWinPtr, abCalcEntryBox);
             PushCalcEntry(entryBox);
+
+            if (!ErrorRaised()) {
                 op->execute();
+            }
+
+            ErrorRaised();
+
             UpdateStack();
         }
 
@@ -373,6 +396,7 @@ void HandleControl(EventRecord *event)
 
         case abCalcBtnEnter:
             PushCalcEntry(entryBox);
+            ErrorRaised();
             UpdateStack();
             break;
 

abCalcNDA.defs

@@ -81,9 +81,11 @@
 #define abCalcBtnPow    2047
 #define abCalcBtnPowStr 2048
 
-#define abCalcEntryBox 2049
-#define abCalcStackList 2050
-#define abCalcOpList 2051
+#define abCalcEntryBox 3001
+#define abCalcStackList 3002
+#define abCalcOpList 3003
+
+#define abCalcErrorAlert 4001
 
 
 #define abCalcWinX 10

abCalcNDA.rez

@@ -453,3 +453,10 @@ resource rControlTemplate (abCalcEntryBox) {
       0                                 /* text Ref */
       }};
    };
+
+resource rAlertString (abCalcErrorAlert) {
+    "23/"
+    "*0"
+    "/^#0\$00"
+};
+

ops/abCOp.c

@@ -72,6 +72,7 @@ static int gNumOps = 0;
 
 void abCalcOpInit(void)
 {
+    gNumOps = 0;
     memset(gOps, 0, sizeof(gOps));
 
     abCalcOpAddInit();