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zeroIndex stuff / ST-80 compatible 0 for empty selection
authorClaus Gittinger <cg@exept.de>
Sat, 20 Apr 1996 15:55:13 +0200
changeset 564 0739243fcc1c
parent 563 fa563ad7630c
child 565 f2a0499ba3d0
zeroIndex stuff / ST-80 compatible 0 for empty selection
SelList.st file | annotate | diff | comparison | revisions
SelectionInList.st file | annotate | diff | comparison | revisions 
--- a/SelList.st	Sat Apr 20 15:54:48 1996 +0200
+++ b/SelList.st	Sat Apr 20 15:55:13 1996 +0200
@@ -120,12 +120,12 @@
 
     ^ AspectAdaptor 
         subject:self 
-        sendsUpdates:true
+        sendsUpdates:false
         accessWith:#selection 
         assignWith:#'selection:' 
         aspect:#selectionIndex
 
-    "Modified: 18.4.1996 / 01:44:15 / cg"
+    "Modified: 20.4.1996 / 12:59:23 / cg"
 !
 
 selectionIndexHolder
@@ -188,27 +188,33 @@
     "whenever one of my holders value changes,
      tell my dependents about this"
 
+    |oldSelection|
+
     changedObject == selectionIndexHolder ifTrue:[
-"/        self notifyChange:#selectionIndex
         self changed:#selectionIndex
     ] ifFalse:[
         changedObject == listHolder ifTrue:[
             something == #value ifTrue:[
-                self clearSelection.
-"/                self notifyChange:#list.
-"/                selectionIndexHolder notifyChange:#value
+                oldSelection := selectionIndexHolder value.
+                self clearSelection.  "/ clears without update
                 self changed:#list.
-                selectionIndexHolder changed:#value
+                oldSelection ~= (selectionIndexHolder value) ifTrue:[
+                    selectionIndexHolder changed:#value
+                ]
             ]
         ]
     ]
+
+    "Modified: 20.4.1996 / 13:08:32 / cg"
 ! !
 
 !SelectionInList methodsFor:'initialization'!
 
 initialize
     self listHolder:(nil asValue).      "/ could also use an empty collection here
-    self selectionIndexHolder:(nil asValue).
+    self selectionIndexHolder:(self zeroIndex asValue).
+
+    "Modified: 20.4.1996 / 13:11:02 / cg"
 ! !
 
 !SelectionInList methodsFor:'obsolete backward compatibility'!
@@ -244,11 +250,25 @@
 !SelectionInList methodsFor:'private'!
 
 clearSelection
-    selectionIndexHolder setValue:0.
+    selectionIndexHolder setValue:self zeroIndex.
+
+    "Modified: 20.4.1996 / 13:11:34 / cg"
+! !
+
+!SelectionInList methodsFor:'queries'!
+
+zeroIndex
+    "return the selections index returned when nothing
+     is selected. Although I would prefer nil,
+     ST-80 uses 0 to represent `no-selection'. (sigh)"
+
+    ^ 0
+
+    "Created: 20.4.1996 / 13:10:53 / cg"
 ! !
 
 !SelectionInList class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libwidg/Attic/SelList.st,v 1.10 1996-04-17 23:56:24 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libwidg/Attic/SelList.st,v 1.11 1996-04-20 13:55:13 cg Exp $'
 ! !
--- a/SelectionInList.st	Sat Apr 20 15:54:48 1996 +0200
+++ b/SelectionInList.st	Sat Apr 20 15:55:13 1996 +0200
@@ -120,12 +120,12 @@
 
     ^ AspectAdaptor 
         subject:self 
-        sendsUpdates:true
+        sendsUpdates:false
         accessWith:#selection 
         assignWith:#'selection:' 
         aspect:#selectionIndex
 
-    "Modified: 18.4.1996 / 01:44:15 / cg"
+    "Modified: 20.4.1996 / 12:59:23 / cg"
 !
 
 selectionIndexHolder
@@ -188,27 +188,33 @@
     "whenever one of my holders value changes,
      tell my dependents about this"
 
+    |oldSelection|
+
     changedObject == selectionIndexHolder ifTrue:[
-"/        self notifyChange:#selectionIndex
         self changed:#selectionIndex
     ] ifFalse:[
         changedObject == listHolder ifTrue:[
             something == #value ifTrue:[
-                self clearSelection.
-"/                self notifyChange:#list.
-"/                selectionIndexHolder notifyChange:#value
+                oldSelection := selectionIndexHolder value.
+                self clearSelection.  "/ clears without update
                 self changed:#list.
-                selectionIndexHolder changed:#value
+                oldSelection ~= (selectionIndexHolder value) ifTrue:[
+                    selectionIndexHolder changed:#value
+                ]
             ]
         ]
     ]
+
+    "Modified: 20.4.1996 / 13:08:32 / cg"
 ! !
 
 !SelectionInList methodsFor:'initialization'!
 
 initialize
     self listHolder:(nil asValue).      "/ could also use an empty collection here
-    self selectionIndexHolder:(nil asValue).
+    self selectionIndexHolder:(self zeroIndex asValue).
+
+    "Modified: 20.4.1996 / 13:11:02 / cg"
 ! !
 
 !SelectionInList methodsFor:'obsolete backward compatibility'!
@@ -244,11 +250,25 @@
 !SelectionInList methodsFor:'private'!
 
 clearSelection
-    selectionIndexHolder setValue:0.
+    selectionIndexHolder setValue:self zeroIndex.
+
+    "Modified: 20.4.1996 / 13:11:34 / cg"
+! !
+
+!SelectionInList methodsFor:'queries'!
+
+zeroIndex
+    "return the selections index returned when nothing
+     is selected. Although I would prefer nil,
+     ST-80 uses 0 to represent `no-selection'. (sigh)"
+
+    ^ 0
+
+    "Created: 20.4.1996 / 13:10:53 / cg"
 ! !
 
 !SelectionInList class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libwidg/SelectionInList.st,v 1.10 1996-04-17 23:56:24 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libwidg/SelectionInList.st,v 1.11 1996-04-20 13:55:13 cg Exp $'
 ! !
hg/stx-libwidg