/ 
any-feature-1.100840
/ any::feature

NAME

any::feature - Backwards-compatible handling of new syntactic features

VERSION

version 1.100840

SYNOPSIS

use any::feature 'say';
say 'Hello, world!';

DESCRIPTION

THE PROBLEM

Perl 5.10 introduces new syntactic features which you can activate and deactivate with the feature module. You want to use the say feature in a program that's supposed to run under both Perl 5.8 and 5.10. So your program looks like this:

use feature 'say';
say 'Hello, world!';

But this only works in Perl 5.10, because there is no feature module in Perl 5.8. So you write

use Perl6::Say;
say 'Hello, world!';

This works, but it's strange to force Perl 5.10 users to install Perl6::Say when the say feature is included in Perl 5.10.

THE SOLUTION

Use any::feature!

WARNING: This is just a proof-of-concept.

any::feature can be used like Perl 5.10's feature and will try to "do the right thing", regardless of whether you use Perl 5.8 or Perl 5.10.

At the moment, this is just a proof-of-concept and only handles the say feature. If things work out, I plan to extend it with other Perl 5.10 features.

The following programs should work and exhibit the same behaviour both in Perl 5.8 and Perl 5.10.

This program will work:

use any::feature 'say';
say 'Hello, world!';

This program will fail at compile-time:

use any::feature 'say';
say 'Hello, world!';

no any::feature 'say';
say 'Oops';

The features are lexically scoped, which is how they work in Perl 5.10:

{
    use any::feature 'say';
    say 'foo';
}
say 'bar';     # dies at compile-time

FUNCTIONS

dispatch

Takes as arguments a direction (activate or deactivate), a package name and a feature name. Activates or deactivates the given feature for the given package.

activate

Takes as arguments a package name and a feature name. Uses dispatch() to activate the given feature in the given package.

deactivate

Takes as arguments a package name and a feature name. Uses dispatch() to deactivate the given feature in the given package.

import

Takes the same arguments as Perl 5.10's use feature pragma. Uses activate() and deactivate() to do its job.

unimport

Takes the same arguments as Perl 5.10's no feature pragma. Uses activate() and deactivate() to do its job.

get_effective_version

Uses Perl::Version to get the version number of the current perl interpreter. This is used to decide the course of action.

get_effective_revision

Uses Perl::Version to get the revision number of the current perl interpreter. This is used to decide the course of action.

INSTALLATION

See perlmodinstall for information and options on installing Perl modules.

BUGS AND LIMITATIONS

No bugs have been reported.

Please report any bugs or feature requests through the web interface at http://rt.cpan.org/Public/Dist/Display.html?Name=any-feature.

AVAILABILITY

The latest version of this module is available from the Comprehensive Perl Archive Network (CPAN). Visit http://www.perl.com/CPAN/ to find a CPAN site near you, or see http://search.cpan.org/dist/any-feature/.

The development version lives at http://github.com/hanekomu/any-feature/. Instead of sending patches, please fork this project using the standard git and github infrastructure.

AUTHOR

Marcel Gruenauer <marcel@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2009 by Marcel Gruenauer.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.