Re: [svn:perl6-synopsis] r11115 - doc/trunk/design/syn
On Fri, Aug 18, 2006 at 12:56:30PM +0300, Markus Laire wrote: : What about combined short switches like C-abc to mean C-a -b -c? : Will perl6 support this notation or not? Hmm, that opens up a world of hurt. Either you have to distinguish a --abc from -abc, or you have to have some kind of fallback heuristic, and it doesn't work terribly well with arguments in any case except for the final one. Should probably make it possible, just because the external interface is one of the places where Perl has always tried to be accommodating to existing culture rather than revisionist. We can probably work something out here, along the lines of: if there's only one - if single character aliases are defined if the word matches that alphabet if the word doesn't match any longer names At first I was inclined to say that if there's a *% then all the unrecognized go in there and you can parse the -abc yourself, but that doesn't tell you how to treat the next argument unless we look at the definition of -c anyway. We can't just say that -c's arg must use the -c=arg form, since even Perl 5 violates that with -e. :/ Larry
Re: [svn:perl6-synopsis] r11115 - doc/trunk/design/syn
On 8/18/06, Larry Wall [EMAIL PROTECTED] wrote: On Fri, Aug 18, 2006 at 12:56:30PM +0300, Markus Laire wrote: : What about combined short switches like C-abc to mean C-a -b -c? : Will perl6 support this notation or not? Hmm, that opens up a world of hurt. Either you have to distinguish a --abc from -abc, or you have to have some kind of fallback heuristic, and it doesn't work terribly well with arguments in any case except for the final one. Should probably make it possible, just because the external interface is one of the places where Perl has always tried to be accommodating to existing culture rather than revisionist. We can probably work something out here, along the lines of: if there's only one - if single character aliases are defined if the word matches that alphabet if the word doesn't match any longer names At first I was inclined to say that if there's a *% then all the unrecognized go in there and you can parse the -abc yourself, but that doesn't tell you how to treat the next argument unless we look at the definition of -c anyway. We can't just say that -c's arg must use the -c=arg form, since even Perl 5 violates that with -e. :/ Larry Yep, I understand it's not an easy question. Still I was thinking of behaviour where C-abc would allways mean C-a -b -c regardless of what 1-char aliases or longer names have been defined. This would make --abc and -abc mean completely different things. And in this proposal only the last switch would be able to get an argument, e.g. with C-abc=99 or C-abc 99 or something like that. If this can't be the default behaviour, then it would be nice to be able to easily switch to this kind of behaviour. ps. Then there's the perl5-behaviour of perl -n0e unlink where also the intervening switches can get arguments. This could be expanded so that all chars for which there's no 1-char alias defined, are parameters. So C-aHellobWorld would mean C-a=Hello -b=World if there are 1-char aliases only for a b. ;) -- Markus Laire
Re: [svn:perl6-synopsis] r11115 - doc/trunk/design/syn
On Fri, Aug 18, 2006 at 07:53:14PM +0300, Markus Laire wrote: : ps. Then there's the perl5-behaviour of perl -n0e unlink where also : the intervening switches can get arguments. This could be expanded so : that all chars for which there's no 1-char alias defined, are : parameters. So C-aHellobWorld would mean C-a=Hello -b=World if : there are 1-char aliases only for a b. ;) I think that safely falls into the category of completely psychotic. @L@ Larry
[svn:perl6-synopsis] r11115 - doc/trunk/design/syn
Author: larry
Date: Thu Aug 17 16:39:38 2006
New Revision: 5
Modified:
doc/trunk/design/syn/S06.pod
Log:
More old use of multiple invocant terminology changed to longnames.
Added mechanism for both short and long switch names.
Modified: doc/trunk/design/syn/S06.pod
==
--- doc/trunk/design/syn/S06.pod(original)
+++ doc/trunk/design/syn/S06.podThu Aug 17 16:39:38 2006
@@ -13,9 +13,9 @@
Maintainer: Larry Wall [EMAIL PROTECTED]
Date: 21 Mar 2003
- Last Modified: 14 Aug 2006
+ Last Modified: 17 Aug 2006
Number: 6
- Version: 49
+ Version: 50
This document summarizes Apocalypse 6, which covers subroutines and the
@@ -481,21 +481,10 @@
print $obj.get_name();
$obj.set_name(Sam);
-Multimethod and multisub invocants are specified at the start of the parameter
-list, with a colon terminating the list of invocants:
-
-multi sub handle_event ($window, $event: $mode) {...} # two invocants
-multi method set_name ($self, $name: $nick) {...} # two invocants
-
-If the parameter list for a Cmulti contains no colon to delimit
-the list of invocant parameters, then all positional parameters are
-considered invocants. If it's a Cmulti method or Cmulti submethod,
-an additional implicit unnamed Cself invocant is prepended to the
-signature list.
-
For the purpose of matching positional arguments against invocant parameters,
the invocant argument passed via the method call syntax is considered the
-first positional argument:
+first positional argument when failover happens from single dispatch to
+multiple dispatch:
handle_event($w, $e, $m); # calls the multi sub
$w.handle_event($e, $m);# ditto, but only if there is no
@@ -509,14 +498,28 @@
# fall-back to set_name($obj, Sam)
$obj.set_name(Sam); # same as the above
-Passing too many or too few invocants is a fatal error if no matching
-definition can be found.
-
An invocant is the topic of the corresponding method or multi if that
formal parameter is declared with the name C$_. A method's first
invocant always has the alias Cself. Other styles of self can be
declared with the Cself pragma.
+=head2 Longname parameters
+
+Much like ordinary methods give preference to the invocant,
+multimethods and multisubs can give preference to earlier parameters.
+These are called Ilongnames; 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; $nick) {...}
+
+If the parameter list for a Cmulti contains no semicolon to delimit
+the list of invocant parameters, then all positional parameters are
+considered invocants. If it's a Cmulti method or Cmulti submethod,
+an additional implicit unnamed Cself invocant is prepended to the
+signature list unless the first parameter is explicitly marked with a colon.
+
=head2 Required parameters
@@ -2534,3 +2537,14 @@
parameters, but still give you access to nested matches through those
parameters, just as any CMatch object would. Of course, in this example,
there's no particular reason the sub has to be named CMAIN.
+
+To give both a long and a short switch name, you may use the pair
+notation. The key will be considered the short switch name, while
+the variable name will be considered the long switch name. So if
+the previous declaration had been:
+
+sub MAIN (:f($frompart), :t($topart), [EMAIL PROTECTED])
+
+then you could invoke the program with either C-f or C--frompart
+to specify the first parameter. Likewise you could use either C-t
+or C--topart for the second parameter.
