Author: larry
Date: Tue Apr 17 11:22:38 2007
New Revision: 14376
Modified:
doc/trunk/design/syn/S04.pod
doc/trunk/design/syn/S05.pod
Log:
Note that unless no longer allows an else
Clarification of binding semantics of if, elsif, and else
Clarification of C<..>. requested by moritz++
Modified: doc/trunk/design/syn/S04.pod
==============================================================================
--- doc/trunk/design/syn/S04.pod (original)
+++ doc/trunk/design/syn/S04.pod Tue Apr 17 11:22:38 2007
@@ -12,9 +12,9 @@
Maintainer: Larry Wall <[EMAIL PROTECTED]>
Date: 19 Aug 2004
- Last Modified: 28 Mar 2007
+ Last Modified: 17 Apr 2007
Number: 4
- Version: 56
+ Version: 57
This document summarizes Apocalypse 4, which covers the block and
statement syntax of Perl.
@@ -175,8 +175,8 @@
=head1 Conditional statements
-The C<if> and C<unless> statements work almost exactly as they do in
-Perl 5, except that you may omit the parentheses on the conditional:
+The C<if> and C<unless> statements work much as they do in
+Perl 5. However, you may omit the parentheses on the conditional:
if $foo == 123 {
...
@@ -192,6 +192,24 @@
branch, the return value is C<undef> in item context and C<()> in
list context.
+The C<unless> statement does not allow an C<elsif> or C<else> in Perl 6.
+
+The value of the conditional expression may be optionally bound to
+a closure parameter:
+
+ if testa() -> $a { say $a }
+ elsif testb() -> $b { say $b }
+ else -> $b { say $b }
+
+Note that the value being evaluated for truth and subsequently bound is
+not necessarily a value of type Bool. (All normal types in Perl may
+be evaluated for truth. In fact, this construct would be relatively
+useless if you could bind only boolean values as parameters, since
+within the closure you already know whether it evaluated to true
+or false.) Binding within an C<else> automatically binds the value
+tested by the previous C<if> or C<elsif>, which, while known to be
+false, might nevertheless be an I<interesting> value of false.
+
Conditional statement modifiers work as in Perl 5. So do the
implicit conditionals implied by short-circuit operators. Note though that
the first expression within parens or brackets is parsed as a statement,
Modified: doc/trunk/design/syn/S05.pod
==============================================================================
--- doc/trunk/design/syn/S05.pod (original)
+++ doc/trunk/design/syn/S05.pod Tue Apr 17 11:22:38 2007
@@ -14,9 +14,9 @@
Maintainer: Patrick Michaud <[EMAIL PROTECTED]> and
Larry Wall <[EMAIL PROTECTED]>
Date: 24 Jun 2002
- Last Modified: 31 Mar 2007
+ Last Modified: 17 Apr 2007
Number: 5
- Version: 56
+ Version: 57
This document summarizes Apocalypse 5, which is about the new regex
syntax. We now try to call them I<regex> rather than "regular
@@ -1137,7 +1137,7 @@
=item *
A leading C<[> or C<+> indicates an enumerated character class. Ranges
-in enumerated character classes are indicated with C<..>.
+in enumerated character classes are indicated with "C<..>" rather than "C<->".
/ <[a..z_]>* /
/ <+[a..z_]>* /
