introduce $^U, a global bit to indicate whether system

[p5sagit/p5-mst-13.2.git] / pod / perldata.pod

diff --git a/pod/perldata.pod b/pod/perldata.pod
index 067c6d9..0b83214 100644 (file)
--- a/pod/perldata.pod
+++ b/pod/perldata.pod
@@ -648,8 +648,12 @@ You couldn't just loop through C<values %hash> to do this because
 that function produces a new list which is a copy of the values,
 so changing them doesn't change the original.
 
-As a special rule, if a list slice would produce a list consisting
-entirely of undefined values, the null list is produced instead.
+A slice of an empty list is still an empty list.  Thus:
+
+    @a = ()[1,0];           # @a has no elements
+    @b = (@a)[0,1];         # @b has no elements
+    @b = (1,undef)[1,0,1];  # @b has three elements
+
 This makes it easy to write loops that terminate when a null list
 is returned: