Artistic License 2.0 makes dual-license boilerplate unnecessary


The dual-licensing in much module boilerplate these days is unnecessary. You can simplify your licensing by using only the Artistic License 2.0.

There are plenty of modules out there that license themselves "under the same terms as Perl itself", and there are problems with that approach. For the past year or so I've been using the approach of being explicit about "Artistic or GPL, your choice", but that's unnecessary, too.

According to Allison Randal, one of the architects of Artistic License 2.0, "Artistic 2 allows for any GPL-like license, not just GPL 2. Specifically, it allows for GPL 3 or later, or a completely non-GPL copyleft license. So, the dual license is unnecessary."

There's a page on the Perl Foundation website about CPAN licensing guidelines that explains more options in more detail.

From here on out, my code is going to say:

=head1 LICENSE

Copyright (C) 2010, Andy Lester,

This module is free software.  You can redistribute it and/or
modify it under the terms of the Artistic License 2.0.

This program is distributed in the hope that it will be useful,
but without any warranty; without even the implied warranty of
merchantability or fitness for a particular purpose.


If I recall early conversations with Larry, the whole purpose of the dual license was that Larry preferred the "Artistic" license, but wasn't sure of its legal validity, and knew that the GPL would be vetted and enforced by the FSF.

Now that Artistic 2 has had similar vetting, and is supported by TPF, there's no purpose in having a more restrictive license like the GPL in the mix.

The thing I like about the "same terms as perl itself" formula is that it makes it clear what my intent is: I'm adding something to the perl project, I want to use it's terms, not my own. I would lean toward GPL 3.0, myself.

I gather that there's supposed to be some ambiguity about whether this means Artistic 1 (note: with GPL 2) or Artistic 2, but I have no idea what it is, even after spending some time reading up on it. What exactly are the grave ramifications of merely using Artistic1/GPL2?

(Hypothetically: suppose you urge CPAN authors to drop the "same terms" phrasing in favor of calling out an explicit license, what happens if they all pick different licenses?)

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