Author: larry
Date: Tue Jan 16 13:27:58 2007
New Revision: 13524
Modified:
doc/trunk/design/syn/S05.pod
Log:
As suggested by pmichaud++, also split C<&> into C<&> and C<&&>,
with only the latter guaranteeing order.
Modified: doc/trunk/design/syn/S05.pod
==============================================================================
--- doc/trunk/design/syn/S05.pod (original)
+++ doc/trunk/design/syn/S05.pod Tue Jan 16 13:27:58 2007
@@ -16,7 +16,7 @@
Date: 24 Jun 2002
Last Modified: 16 Jan 2007
Number: 5
- Version: 42
+ Version: 43
This document summarizes Apocalypse 5, which is about the new regex
syntax. We now try to call them I<regex> rather than "regular
@@ -79,7 +79,7 @@
A logical alternation using C<|> then takes two or more of these lists
and dispatches to the alternative that advertises the longest matching
prefix, not necessarily to the alternative that comes first lexically.
-(However, in the case of a tie between alternatives, the first earlier
+(However, in the case of a tie between alternatives, the earlier
alternative does take precedence.)
Initial constants must take into account case sensitivity (or any other
@@ -497,10 +497,20 @@
=item *
-The new C<&> metacharacter separates conjunctive terms. The patterns on
-either side must match with the same beginning and end point. The
-operator is list associative like C<|>, has higher precedence than C<|>,
-and backtracking makes the right argument vary faster than the left.
+The new C<&> metacharacter separates conjunctive terms. The patterns
+on either side must match with the same beginning and end point.
+Note: if you don't want your two terms to end at the same point,
+then you really want to use a lookahead instead.
+
+As with the disjunctions C<|> and C<||>, conjuctions come in both
+C<&> and C<&&> forms. The C<&> form allows the compiler and/or the
+run-time system to decide which parts to evaluate first, and it is
+erroneous to assume either order happens consistently. The C<&&>
+form short-circuits, and backtracking makes the right argument vary
+faster than the left.
+
+The C<&> and C<&&> operators are list associative like C<|> and C<||>,
+but have tighter precedence.
=back
