diff -r 429ec70365a6 -r 9ebf6de8a764 OrderedCollection.st
--- a/OrderedCollection.st	Thu Jul 30 18:05:41 1998 +0200
+++ b/OrderedCollection.st	Thu Jul 30 18:06:34 1998 +0200
@@ -663,7 +663,8 @@
 !
 
 removeFirst
-    "remove the first element from the collection; return the element."
+    "remove the first element from the collection; return the element.
+     If there is no element in the receiver collection, raise an error."
 
     |anObject fI "{ Class: SmallInteger }" |
 
@@ -695,7 +696,7 @@
      (SortedCollection withAll:#(5 4 3 2 1)) removeFirst; yourself
     "
 
-    "Modified: / 12.11.1997 / 17:58:43 / cg"
+    "Modified: / 30.7.1998 / 13:19:59 / cg"
 !
 
 removeFirst:n
@@ -738,6 +739,45 @@
     "Modified: 8.2.1997 / 19:20:18 / cg"
 !
 
+removeFirstIfAbsent:exceptionBlock
+    "remove the first element from the collection; return the element.
+     If there is no element in the receiver collection, return the value from
+     exceptionBlock."
+
+    |anObject fI "{ Class: SmallInteger }" |
+
+    fI := firstIndex.
+
+    fI > lastIndex ifTrue:[
+        "error if collection is empty"
+        ^ exceptionBlock value.
+    ].
+
+    anObject := contentsArray basicAt:fI.
+
+    "/ nil it out, to allow GC to reclaim it.
+    contentsArray basicAt:fI put:nil.
+
+    fI := fI + 1.
+
+    fI > lastIndex ifTrue:[
+        "reset to avoid ever growing"
+        fI := 1.
+        lastIndex := 0 
+    ].
+    firstIndex := fI.
+    ^ anObject
+
+    "
+     (OrderedCollection withAll:#(1 2 3 4 5)) removeFirst; yourself
+     OrderedCollection new removeFirst
+     (SortedCollection withAll:#(5 4 3 2 1)) removeFirst; yourself
+    "
+
+    "Modified: / 12.11.1997 / 17:58:43 / cg"
+    "Created: / 30.7.1998 / 13:19:42 / cg"
+!
+
 removeFrom:startIndex to:stopIndex
     "added for ST-80 compatibility.
      Same as removeFromIndex:toIndex:."
@@ -1725,5 +1765,5 @@
 !OrderedCollection class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libbasic/OrderedCollection.st,v 1.67 1998-04-07 11:38:56 ca Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic/OrderedCollection.st,v 1.68 1998-07-30 16:06:34 cg Exp $'
 ! !