--- a/Collection.st	Thu Jan 22 00:23:21 2009 +0100
+++ b/Collection.st	Thu Jan 22 21:24:47 2009 +0100
@@ -228,6 +228,7 @@
     ^ self withSize:n
 ! !
 
+
 !Collection class methodsFor:'Signal constants'!
 
 emptyCollectionSignal
@@ -383,6 +384,7 @@
     ].
 ! !
 
+
 !Collection methodsFor:'accessing'!
 
 anElement
@@ -1040,16 +1042,15 @@
      Consider a collection of measurement or physical objects, 0 would be the unitless 
      value and would not be appropriate to add with the unit-ed objects."
 
-    self emptyCheck.
+    self isEmpty ifTrue:[^ 0].
+
     ^ self 
         inject:(self first class zero) 
         into:[:accum :each | accum + each].
     
 
     "
-     TestCase should: [ { } sum ] raise:Error.
-     TestCase should: [ ''  sum ] raise:Error.
-
+     TestCase assert: ( {  } sum = 0 ).
      TestCase assert: ( { 1 } sum = 1 ).
      TestCase assert: ( { 1. 2. 3. 4. } sum = 10 ).
      TestCase assert: ( (1 to:10) sum = 55 ).
@@ -2381,7 +2382,6 @@
 ! !
 
 
-
 !Collection methodsFor:'operations'!
 
 decrementAt:aKey
@@ -3340,7 +3340,7 @@
 !Collection class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libbasic/Collection.st,v 1.216 2009-01-16 13:55:49 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic/Collection.st,v 1.217 2009-01-22 20:24:47 cg Exp $'
 ! !
 
 Collection initialize!