Perl6::Export::Attrs(3)

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

VERSION
This document describes Perl6::Export::Attrs version 0.0.3

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!";
        }

        IMPORT {
                # This block is called when the module is used (as usual),
                # but it is called after any export requests have been handled.
                # Those requests will have been stripped from its @_ argument list
    }

DESCRIPTION
Implements a Perl 5 native version of what the Perl 6 symbol export mechanism will look like.

It's very straightforward:

•   If you want a subroutine 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 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 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 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. However, any export specifications (names of subroutines or tagsets to be exported) will have already been removed from that argument list before "IMPORT" receives it.

DIAGNOSTICS

%s does not export: %s\nuse %s failed
    You tried to import the specified subroutine, 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 in question.

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

Internal error: missing symbol for %s
    A subroutine was specified as being exported during module compilation but mysteriously ceased to exist before the module was imported.

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
None reported.

BUGS AND LIMITATIONS
No bugs have been reported. Note that the module does not support exporting variables. This is considered a feature, not a bug. See Chapter 17 of Perl Best Practices (O'Reilly, 2005).

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.