Damian Conway

NAME

Perl6::Export - Implements the Perl 6 'is export(...)' trait

SYNOPSIS

    # Perl 5 code...

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

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

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


    # Export &bar 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 is export(:DEFAULT :bees :pubs) {
        print "baaa!";
    }


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

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


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

    sub qux is 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 what I hope the Perl 6 symbol export mechanism might 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 is export trait.

  • If you want a subroutine to be automatically exported when the module is used (without specific overriding arguments), you mark it with the is export(:DEFAULT) trait.

  • 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 is export(:MANDATORY) trait.

  • If the subroutine should also be exported when particular export groups are requested, you add the names of those export groups to the trait'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.

Perl6::Export honours either the Perl5-ish:

    sub import {...}

or the equivalent Perl6-ish:

    IMPORT {...}

In either case the subroutine/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/IMPORT receives it.

WARNING

The syntax and semantics of Perl 6 is still being finalized and consequently is at any time subject to change. That means the same caveat applies to this module.

DEPENDENCIES

Requires Filter::Simple

AUTHOR

Damian Conway (damian@conway.org)

BUGS AND IRRITATIONS

Does not yet handle the export of variables. The author personally believes this is a feature, rather than a bug.

Comments, suggestions, and patches welcome.

COPYRIGHT

 Copyright (c) 2003, Damian Conway. All Rights Reserved.
 This module is free software. It may be used, redistributed
    and/or modified under the same terms as Perl itself.