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Postings from July 2008
Author: larry
Date: Thu Jul 17 10:57:24 2008
New Revision: 14567
Modified:
doc/trunk/design/syn/S09.pod
Log:
Equivalence of cascaded and semicolon subscript forms suggested by nick++
Modified: doc/trunk/design/syn/S09.pod
==============================================================================
--- doc/trunk/design/syn/S09.pod (original)
+++ doc/trunk/design/syn/S09.pod Thu Jul 17 10:57:24 2008
@@ -12,9 +12,9 @@
Maintainer: Larry Wall <larry@wall.org>
Date: 13 Sep 2004
- Last Modified: 27 May 2008
+ Last Modified: 17 July 2008
Number: 9
- Version: 27
+ Version: 28
=head1 Overview
@@ -776,6 +776,27 @@
@x[0;1;42]
+=head1 Cascaded subscripting of multidimensional arrays
+
+For all multidimensional array types, it is expected that cascaded subscripts:
+
+ @x[0][1][42]
+ @x[0..10][1,0][1..*:by(2)]
+
+will either fail or produce the same results as the equivalent
+semicolon subscripts:
+
+ @x[0;1;42]
+ @x[0..10; 1,0; 1..*:by(2)]
+
+Built-in array types are expected succeed either way, even if
+the cascaded subscript form must be implemented inefficiently by
+constructing temporary slice objects for later subscripts to use.
+(User-defined types may choose not to support the cascaded form, but
+if so, they should fail rather than providing different semantics.)
+As a consequence, for built-in types of declared shape, the appropriate
+number of cascaded subscripts may always be optimized into the
+semicolon form.
=head1 The semicolon operator