Reorganize _parse_modify() to remove spurious warnings

about used-before-set variables, and avoid extra re matching
when not needed.

Author: rthalley

dns/zonefile.py

@@ -279,31 +279,31 @@ def _parse_modify(self, side: str) -> Tuple[str, str, int, int, str]:
         # Sometimes there are modifiers in the hostname. These come after
         # the dollar sign. They are in the form: ${offset[,width[,base]]}.
         # Make names
+        mod = ""
+        sign = "+"
+        offset = 0
+        width = 0
+        base = "d"
         g1 = is_generate1.match(side)
         if g1:
             mod, sign, offset, width, base = g1.groups()
             if sign == "":
                 sign = "+"
-        g2 = is_generate2.match(side)
-        if g2:
-            mod, sign, offset = g2.groups()
-            if sign == "":
-                sign = "+"
-            width = 0
-            base = "d"
-        g3 = is_generate3.match(side)
-        if g3:
-            mod, sign, offset, width = g3.groups()
-            if sign == "":
-                sign = "+"
-            base = "d"
-
-        if not (g1 or g2 or g3):
-            mod = ""
-            sign = "+"
-            offset = 0
-            width = 0
-            base = "d"
+        else:
+            g2 = is_generate2.match(side)
+            if g2:
+                mod, sign, offset = g2.groups()
+                if sign == "":
+                    sign = "+"
+                width = 0
+                base = "d"
+            else:
+                g3 = is_generate3.match(side)
+                if g3:
+                    mod, sign, offset, width = g3.groups()
+                    if sign == "":
+                        sign = "+"
+                    base = "d"
 
         offset = int(offset)
         width = int(width)