NAME

       Perl6::Export::Attrs - The Perl 6 'is export(...)' trait as a Perl 5 attribute

VERSION

       This document describes Perl6::Export::Attrs version 0.000005

SYNOPSIS

           package Some::Module;
           use Perl6::Export::Attrs;

           # Export &foo by default, when explicitly requested,
           # or when the ':ALL' export set is requested...

           sub foo :Export(:DEFAULT) {
               print "phooo!";
           }

           # Export &var by default, when explicitly requested,
           # or when the ':bees', ':pubs', or ':ALL' export set is requested...
           # the parens after 'is export' are like the parens of a qw(...)

           sub bar :Export(:DEFAULT :bees :pubs) {
               print "baaa!";
           }

           # Export &baz when explicitly requested
           # or when the ':bees' or ':ALL' export set is requested...

           sub baz :Export(:bees) {
               print "baassss!";
           }

           # Always export &qux
           # (no matter what else is explicitly or implicitly requested)

           sub qux :Export(:MANDATORY) {
               print "quuuuuuuuux!";
           }

           # Allow the constant $PI to be exported when requested...

           use Readonly;
           Readonly our $PI :Export => 355/113;

           # Allow the variable $EPSILON to be always exported...

           our $EPSILON :Export( :MANDATORY ) = 0.00001;

           sub IMPORT {
               # This subroutine is called when the module is used (as usual),
               # but it is called after any export requests have been handled.
           };

DESCRIPTION

       Implements a Perl 5 native version of what the Perl 6 symbol export mechanism will look
       like (with some unavoidable restrictions).

       It's very straightforward:

       •   If you want a subroutine or package variable to be capable of being exported (when
           explicitly requested in the "use" arguments), you mark it with the ":Export"
           attribute.

       •   If you want a subroutine or package variable to be automatically exported when the
           module is used (without specific overriding arguments), you mark it with the
           ":Export(:DEFAULT)" attribute.

       •   If you want a subroutine or package variable to be automatically exported when the
           module is used (even if the user specifies overriding arguments), you mark it with the
           ":Export(:MANDATORY)" attribute.

       •   If the subroutine or package variable should also be exported when particular export
           groups are requested, you add the names of those export groups to the attribute's
           argument list.

       That's it.

   "IMPORT" blocks
       Perl 6 replaces the "import" subroutine with an "IMPORT" block. It's analogous to a
       "BEGIN" or "END" block, except that it's executed every time the corresponding module is
       "use"'d.

       The "IMPORT" block is passed the argument list that was specified on the "use" line that
       loaded the corresponding module, minus the arguments that were used to specify exports.

       Note that, due to limitations in Perl 5, the "IMPORT" block provided by this module must
       be terminated by a semi-colon, unless it is the last statement in the file.

DIAGNOSTICS

       %s does not export: %s\nuse %s failed
           You tried to import the specified subroutine or package variable, but the module
           didn't export it. Often caused by a misspelling, or forgetting to add an ":Export"
           attribute to the definition of the subroutine or variable in question.

       Bad tagset in :Export attribute at %s line %s: [%s]
           You tried to import a collection of items via a tagset, but the module didn't export
           any subroutines under that tagset. Is the tagset name misspelled (maybe you forgot the
           colon?).

       Can't export lexical %s variable at %s
           The module can only export package variables. You applied the ":Export" marker to a
           non-package variable (almost certainly to a lexical). Change the variable's "my"
           declarator to an "our".

       Can't export anonymous subroutine at %s
           Although you can apply the ":Export" marker to an anonymous subroutine, it rarely
           makes any sense to do so, since that subroutine can't be exported without a name to
           export it as. Either give the subroutine a name, or make sure it's aliased to a named
           typeglob at compile-time (or, at least, before it's exported).

CONFIGURATION AND ENVIRONMENT

       Perl6::Export::Attrs requires no configuration files or environment variables.

DEPENDENCIES

       This module requires the Attribute::Handlers module to handle the attributes.

INCOMPATIBILITIES

       This module cannot be used with the Memoize CPAN module, because memoization replaces the
       original subroutine with a wrapper. Because the ":Export" attribute is applied to the
       original (not the wrapper), the memoized wrapper is not found by the exporter mechanism.

BUGS AND LIMITATIONS

       No bugs have been reported.

       Note that the module does not support exporting lexical variables, since there is no way
       for the exporter mechanism to determine the name of a lexical and hence to export it.

       Nor does this module support the numerous addition export modes that Perl 6 offers, such
       as export-as-lexical or export-as-state.

       Please report any bugs or feature requests to "bug-perl6-export-attrs@rt.cpan.org", or
       through the web interface at <http://rt.cpan.org>.

AUTHOR

       Damian Conway  "<DCONWAY@cpan.org>"

LICENCE AND COPYRIGHT

       Copyright (c) 2005, Damian Conway "<DCONWAY@cpan.org>". All rights reserved.

       This module is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.

DISCLAIMER OF WARRANTY

       BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE,
       TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE
       COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF
       ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
       WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO
       THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE
       DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

       IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT
       HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY
       THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
       INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
       SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR
       LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY
       OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
       SUCH DAMAGES.