Author: audreyt
Date: Wed Mar 7 09:10:48 2007
New Revision: 14314
Modified:
doc/trunk/design/syn/S06.pod
Log:
* S06: Instead of introducing the conjectural concept of
single-semicolon delimited multiple-longnames, delegate
the discussion to S12 and present the non-controversial
double-semicolon form as the example instead.
Modified: doc/trunk/design/syn/S06.pod
==============================================================================
--- doc/trunk/design/syn/S06.pod (original)
+++ doc/trunk/design/syn/S06.pod Wed Mar 7 09:10:48 2007
@@ -13,9 +13,9 @@
Maintainer: Larry Wall <[EMAIL PROTECTED]>
Date: 21 Mar 2003
- Last Modified: 28 Feb 2007
+ Last Modified: 8 Mar 2007
Number: 6
- Version: 73
+ Version: 74
This document summarizes Apocalypse 6, which covers subroutines and the
@@ -510,22 +510,24 @@
=head2 Longname parameters
-Much like ordinary methods give preference to the invocant,
-multimethods and multisubs can give preference to earlier parameters.
-These are called I<longnames>; see S12 for more about the semantics
-of multiple dispatch. Syntactically, longnames are declared by
-terminating the list of important parameters with a semicolon:
-
- multi sub handle_event ($window, $event; $mode) {...}
- multi method set_name ($self: $name; $nick) {...}
-
-A double semicolon terminates the longest possible longname; parameters
-after this are never considered for multiple dispatch (except of course
-that they can still "veto" if their number or types mismatch). (Note,
-the single semicolon form is still considered conjectural, though the
-double semicolon is fairly certain.)
+Routines marked with C<multi> can mark part of its parameters to
+be considered in the multi dispatch. These are called I<longnames>;
+see S12 for more about the semantics of multiple dispatch.
-If the parameter list for a C<multi> contains no semicolon to delimit
+You can choose part of a C<multi>'s parameters to be its longname,
+by putting a double semicolon after the last one:
+
+ multi sub handle_event ($window, $event;; $mode) {...}
+ multi method set_name ($self: $name;; $nick) {...}
+
+A parameter list may have at most one double semicolon; parameters
+after it are never considered for multiple dispatch (except of course
+that they can still "veto" if their number or types mismatch).
+
+[Conjecture: It might be possible for a routine to advertise multiple
+long names, delimited by single semicolons. See S12 for details.]
+
+If the parameter list for a C<multi> contains no semicolons to delimit
the list of important parameters, then all positional parameters are
considered important. If it's a C<multi method> or C<multi submethod>,
an additional implicit unnamed C<self> invocant is added to the
@@ -745,8 +747,8 @@
is required at least for its types, or the declaration would not know
what signature to match against.
- multi foo (|$args (Int; Bool?, *@, *%)) { reallyintfoo($args) }
- multi foo (|$args (Str; Bool?, *@, *%)) { reallystrfoo($args) }
+ multi foo (|$args (Int, Bool?, *@, *%)) { reallyintfoo($args) }
+ multi foo (|$args (Str, Bool?, *@, *%)) { reallystrfoo($args) }
=head2 Flattening argument lists
