--- a/Structure.st	Thu Jun 02 11:29:55 2016 +0200
+++ b/Structure.st	Fri Jun 03 02:57:50 2016 +0200
@@ -1,3 +1,5 @@
+"{ Encoding: utf8 }"
+
 "
  COPYRIGHT (c) 1996 by Claus Gittinger
               All Rights Reserved
@@ -13,13 +15,13 @@
 
 "{ NameSpace: Smalltalk }"
 
-Object subclass:#Structure
-	instanceVariableNames:'superclass flags methodDictionary lookupFunction instSize i1 i2
-		i3 i4 i5 i6 i7 i8 i9 i10 i11 i12 i13 i14 i15 i16 i17 i18 i19 i20
-		i21 i22 i23 i24 i25 i26 i27 i28 i29 i30 i31 i32 i33 i34 i35 i36
-		i37 i38 i39 i40 i41 i42 i43 i44 i45 i46 i47 i48 i49 i50'
+Behavior subclass:#Structure
+	instanceVariableNames:'i1 i2 i3 i4 i5 i6 i7 i8 i9 i10 i11 i12 i13 i14 i15 i16 i17 i18
+		i19 i20 i21 i22 i23 i24 i25 i26 i27 i28 i29 i30 i31 i32 i33 i34
+		i35 i36 i37 i38 i39 i40 i41 i42 i43 i44 i45 i46 i47 i48 i49 i50'
 	classVariableNames:'OneInstance DummyClass ReadAccessMethods WriteAccessMethods
-		OtherMethods OtherSelectors'
+		OtherMethods OtherSelectors IndexOfFlags IndexOfMethodDictionary
+		IndexOfInstSize'
 	poolDictionaries:''
 	category:'Programming-Support'
 !
@@ -126,10 +128,13 @@
     OneInstance isNil ifTrue:[
         "/ check if the first few instvars correspond to Behavior's definition:
 
-        (Behavior instSize + 1) == (self instanceVariableNames indexOf:#i1) ifFalse:[
-            self halt:'you must change the definition of this class (instvars before i1 must match behavior''s)'.
-        ].
-
+"/        (Behavior instSize + 1) == (self instanceVariableNames indexOf:#i1) ifFalse:[
+"/            self halt:'you must change the definition of this class (instvars before i1 must match behavior''s)'.
+"/        ].
+        IndexOfFlags := Behavior instVarIndexFor:'flags'.
+        IndexOfMethodDictionary := Behavior instVarIndexFor:'methodDictionary'. 
+        IndexOfInstSize := Behavior instVarIndexFor:'instSize'. 
+        
         OneInstance := self basicNew.
 
         DummyClass := Behavior shallowCopy.
@@ -234,11 +239,11 @@
 
     arr := Array new:(behviorsInstSize + nInsts).
 "/    arr at:1 put:nil.                                                   "/ superclass
-    arr at:2 put:(Behavior flagBehavior bitOr:Behavior flagPointers).   "/ flags
-    arr at:3 put:(MethodDictionary withKeys:sels andValues:mthds).      "/ selectors & methods
-"/    arr at:4 put:nil.                                                   "/ lookupObject
-    arr at:5 put:behviorsInstSize.                                      "/ instSize
-
+    arr at:IndexOfFlags put:(Behavior flagBehavior bitOr:Behavior flagPointers).          "/ flags
+    arr at:IndexOfMethodDictionary put:(MethodDictionary withKeys:sels andValues:mthds).  "/ selectors & methods
+"/    arr at:IndexOfLookupObject put:nil.                                                 "/ lookupObject
+    arr at:IndexOfInstSize put:behviorsInstSize.                                      "/ instSize
+    
     "/ now, the big trick ...
 
     arr changeClassTo:DummyClass.