Author: moritz Date: 2009-07-27 20:54:44 +0200 (Mon, 27 Jul 2009) New Revision: 27755
Modified: docs/Perl6/Spec/S06-routines.pod docs/Perl6/Spec/S29-functions.pod Log: get rid of want(), it's not implementable See <http://www.nntp.perl.org/group/perl.perl6.language/2009/03/msg31372.html> for a discussion where nobody stood up in defense of want(). Modified: docs/Perl6/Spec/S06-routines.pod =================================================================== --- docs/Perl6/Spec/S06-routines.pod 2009-07-27 15:36:39 UTC (rev 27754) +++ docs/Perl6/Spec/S06-routines.pod 2009-07-27 18:54:44 UTC (rev 27755) @@ -2090,7 +2090,6 @@ .context .caller .leave - .want .inline .package .file @@ -2101,8 +2100,7 @@ The C<.context> and C<.caller> methods work the same as the functions except that they are relative to the context supplied as invocant. The C<.leave> method can force an immediate return from the -specified context. The C<.want> method returns known smart-matchable -characteristics of the specified context. +specified context. The C<.inline> method says whether this block was entered implicitly by some surrounding control structure. Any time you invoke a block or @@ -2124,44 +2122,21 @@ =head2 The C<want> function -The C<want> function returns a C<Signature> object that contains -information about the context in which the current block, closure, -or subroutine was called. The C<want> function is really just -short for C<caller.want>. (Note that this is what your current -routine's caller wants from your routine, not necessarily the same as -C<context.want> when you are embedded in a block within a subroutine. -Use C<context.want> if that's what you want.) +The C<want> function is gone. If you want context specific behavior, +return an object instead that responds accordingly to the various contextual +methods. -As with normal function signatures, you can test the result of C<want> with a -smart match (C<~~>) or a C<when>: +(Conjecture: in future we might want to provide some syntactic sugar that +makes it easier to create such objects. Or maybe a type that takes values +or code references for the various contexts, so that you can write - given want { - when :($) {...} # called in item context - when :(*@) {...} # called in list context - when :($ is rw) {...} # expected to return an lvalue - when :($,$) {...} # expected to return two values - ... - } + return ContextProxy.new: + Int => 3, + item => { @.list.join(', ') }, + liste => { ... }, + ; +or something similar.) -Or use its shorthand methods to reduce line noise: - - if want.item {...} # called in non-lvalue item context - elsif want.list {...} # called in list context - elsif want.void {...} # called in void context - elsif want.rw {...} # expected to return an lvalue - -The C<.arity> and C<.count> methods also work here: - - if want.arity > 2 {...} # must return more than two values - if want.count > 2 {...} # can return more than two values - -Their difference is that C<.arity> considers only mandatory parts, -while C<.count> considers also optional ones, including C<*$>: - - ($x, $y) = f(); # Within &f, want === :(*$?, *$?, *@) - # want.arity === 0 - # want.count === 2 - =head2 The C<leave> function As mentioned above, a C<return> call causes the innermost surrounding Modified: docs/Perl6/Spec/S29-functions.pod =================================================================== --- docs/Perl6/Spec/S29-functions.pod 2009-07-27 15:36:39 UTC (rev 27754) +++ docs/Perl6/Spec/S29-functions.pod 2009-07-27 18:54:44 UTC (rev 27755) @@ -250,10 +250,6 @@ See C<Synopsis 17: Concurrency> for more details. -=item want - -See L<S06/The C<want> function>. - =item die =item fail
