Author: larry
Date: Wed Jun 28 19:50:48 2006
New Revision: 9722
Modified:
doc/trunk/design/syn/S12.pod
Log:
enum clarifications from dduncan++
Modified: doc/trunk/design/syn/S12.pod
==============================================================================
--- doc/trunk/design/syn/S12.pod (original)
+++ doc/trunk/design/syn/S12.pod Wed Jun 28 19:50:48 2006
@@ -12,9 +12,9 @@
Maintainer: Larry Wall <[EMAIL PROTECTED]>
Date: 27 Oct 2004
- Last Modified: 20 Jun 2006
+ Last Modified: 28 Jun 2006
Number: 12
- Version: 16
+ Version: 17
=head1 Overview
@@ -1295,39 +1295,45 @@
An enum is a low-level class that can function as a role or property.
A given enum value can function as a subtype, a method, or as an ordinary
-value (an argumentless sub). The values are specified as a list:
+value (an argumentless sub). The names of the values are specified as a list:
- my enum day ['Sun','Mon','Tue','Wed','Thu','Fri','Sat'];
- my enum day <Sun Mon Tue Wed Thu Fri Sat>;
+ my enum Day ['Sun','Mon','Tue','Wed','Thu','Fri','Sat'];
+ my enum Day <Sun Mon Tue Wed Thu Fri Sat>;
-The default return type is C<int> or C<str> depending on the type of
-the first value. The type can be specified:
+If the first value is unspecified, it defaults to 0. To specify the
+first value, use pair notation (see below).
+
+If the declared type name begins with an uppercase letter, the default
+type is C<Int> or C<Str>, depending on the type of the first value.
+If the declared type is lowercase, the default return type is C<int> or C<buf>.
+
+The type can be specified:
my bit enum maybe <no yes>;
- my int enum day ['Sun','Mon','Tue','Wed','Thu','Fri','Sat'];
- my enum day of int <Sun Mon Tue Wed Thu Fri Sat>;
- my enum day returns int <Sun Mon Tue Wed Thu Fri Sat>;
+ my Int enum day ['Sun','Mon','Tue','Wed','Thu','Fri','Sat'];
+ my enum day of uint4 <Sun Mon Tue Wed Thu Fri Sat>;
An anonymous enum just makes sure each string turns into a pair with
sequentially increasing values, so:
- %enum = enum < ook! ook. ook? >;
+ %e = enum < ook! ook. ook? >;
is equivalent to:
- %enum = ();
- %enum<ook!> = 0;
- %enum<ook.> = 1;
- %enum<ook?> = 2;
+ %e = ();
+ %e<ook!> = 0;
+ %e<ook.> = 1;
+ %e<ook?> = 2;
The enum installer inspects list values for pairs, where the value
of the pair sets the next value explicitly. Non-pairs C<++> the
-previous value. Since the C<«...»> quoter automatically recognizes
+previous value. (Str and buf types increment like Perl 5 strings.)
+Since the C<«...»> quoter automatically recognizes
pair syntax along with interpolations, we can simply say:
my enum DayOfWeek «:Sun(1) Mon Tue Wed Thu Fri Sat»;
- our str enum Phonetic «:Alpha<A> Bravo Charlie Delta
+ our Str enum Phonetic «:Alpha<A> Bravo Charlie Delta
Echo Foxtrot Golf Hotel India Juliet
Kilo Lima Mike November Oscar Papa
Quebec Romeo Sierra Tango Uniform
