/ 
Exporter-Simple-0.13
River stage one • 2 direct dependents • 2 total dependents
/ Exporter::Simple

NAME

Exporter::Simple - Easier set-up of module exports

SYNOPSIS

package MyExport;
use Exporter::Simple;

my @bar : Exportable(vars) = (2, 3, 5, 7);
my $foo : Exported(vars)   = 42;
my %baz : Exported         = (a => 65, b => 66);

sub hello : Exported(greet,uk)   { "hello there" }
sub askme : Exportable           { "what you will" }
sub hi    : Exportable(greet,us) { "hi there" }

# meanwhile, in a module far, far away
use MyExport qw(:greet);
print hello();
$baz{c} = 67;

DESCRIPTION

This module, when used by a package, allows that package to define exports in a more concise way than using Exporter. Instead of having to worry what goes in @EXPORT, @EXPORT_OK and %EXPORT_TAGS, you can use two attributes to define exporter behavior. This has two advantages: It frees you from the implementation details of Exporter, and it keeps the export definitions where they belong, with the subroutines and variables.

The attributes provided by this module are:

Exported

Indicates that the associated subroutine or lexical variable should be automatically exported. It will also go into the :all tag (per the rules of %EXPORT_TAGS), as well as any tags you specify as options of this attribute.

For example, the following declaration

sub hello : Exported(greet,uk)   { ... }

will cause hello() to be exported, but also be available in the tags :all, :greet and :uk.

Exportable

Is like Exported, except that the associated subroutine or lexical variable won't be automatically exported. It will still go to the :all tag in any case and all other tags specified as attribute options.

Exporting Lexical Variables

Exporter::Simple allows you to export lexical variables; something Exporter can't do. What happens is that the lexical is aliased to a global of the same name, which is then exported. So when you manipulate that global, you're really manipulating the lexical.

The syntax for exporting lexical variables is the same as for subroutines as lexicals can take attributes just as subroutines do.

Exporter::Simple expects some cooperation from you when exporting lexicals. For reasons best explained by reading the (commented) source, you need to make sure to have

1;

as the last line of code in your module. This is the true value you have to return from the module anyway.

Exporting Global Variables

Global variables can't take attributes as of Perl 5.6.0, so it's necessary to export globals manually. This needs to happen during BEGIN() though, so you need to write code like this:

BEGIN {
  export([ qw/EXPORTED_CONST @array $friend/ ], 'globals');
  exportable('EXPORTABLE_CONST', 'globals');
}

Urgh.

However, globals will be able to take attributes in Perl 5.8.0, and this module will then be updated to reflect those capabilities.

The two subroutines used to export globals are:

export($symbols, $tags)

As shown in the example above, both arguments can be either strings (to indicate one symbol or tag) or array references to indicate multiple symbols or tags.

The semantics are the same as for the Export attribute above.

exportable($symbols, $tags)

As export(), but does not automatically export the symbols. The semantics are the same as for the Exportable attribute above.

These two subroutines are automatically exported by Exporter::Simple. The reason for this brute-force export is that these subroutines need to be used during BEGIN, but Exporter::Simple doesn't have a chance to use Exporter to export those two subroutines yet. Sigh.

TODO

reflection

Retrieve information about exports

test using two exporting modules

To see whether Exporter::Simple is ok with more than one module using it. (I don't know why it shouldn't be, but that's what testing is for).

BUGS

If you find any bugs or oddities, please do inform the author.

AUTHOR

Marcel Grünauer <marcel.gruenauer@chello.at>

CONTRIBUTORS

Damian Conway <damian@conway.org> Richard Clamp <richardc@unixbeard.net>

COPYRIGHT

Copyright 2001-2002 Marcel Grünauer. All rights reserved.

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

SEE ALSO

perl(1), Attribute::Handlers(3pm), Exporter(3pm).