Base Perl modules with BSD software

[Alex Hanson]

I am writing a piece of software that I want to license as BSD. I am
using Perl, which is licensed under both the GPL and its own Artistic
License.

According to the GNU website (
http://www.gnu.org/licenses/gpl-faq.html#IfInterpreterIsGPL ) my program
will be considered a derivative work if "the interpreter is extended to
provide 'bindings' to other facilities". As far as I know, Perl modules
do not fall under that category since they do not change the interpreter
in any way.

What concerns me is a later part of the article that reads "if you
choose to use GPL'd Perl modules or Java classes in your program, you
must release the program in a GPL-compatible way". This makes sense for
the 3rd modules found on CPAN and other websites, but what about the
modules included with Perl? Could a statement as simple as "use Carp"
force my program to be licensed under the GPL?

Thanks for your help.

-Alex Hanson

[Matthew Flaschen]

Alex wrote:

> I am writing a piece of software that I want to license as BSD. I am
> using Perl, which is licensed under both the GPL and its own Artistic
> License.
>
> According to the GNU website (
> http://www.gnu.org/licenses/gpl-faq.html#IfInterpreterIsGPL ) my program
> will be considered a derivative work if "the interpreter is extended to
> provide 'bindings' to other facilities". As far as I know, Perl modules
> do not fall under that category since they do not change the interpreter
> in any way.

Yes, but I think some do have this kind of bindings.  For example, there
was a discussion before of the GNU Readline module
(http://search.cpan.org/dist/Term-ReadLine-Gnu/) which provides a
binding for GNU Readline(GPL-only).  By the FSF's interpretation, I
believe a program that
uses Term GNU Readline  would need to be released under the GPL.

> what about the modules included with Perl? Could a statement as simple as "use Carp"
> force my program to be licensed under the GPL?

I believe most of the modules included in Perl use Artistic/GPL.
Artistic is explicitly not a copyleft license, and says, "The scripts
and library files supplied as input to or produced as output from the
programs of this Package do not automatically fall under the copyright
of this Package, but belong to whomever generated them, and may be sold
commercially, and may be aggregated with this Package."  That means if
you only use Perl/Artistic modules you shouldn't have to be under the GPL.

Matthew Flaschen

[Allison Randal]

Matthew Flaschen wrote:

> Alex wrote:
>> I am writing a piece of software that I want to license as BSD. I am
>> using Perl, which is licensed under both the GPL and its own Artistic
>> License.
>
>> what about the modules included with Perl? Could a statement as simple as "use Carp"
>> force my program to be licensed under the GPL?
>
> I believe most of the modules included in Perl use Artistic/GPL.
> Artistic is explicitly not a copyleft license, and says, "The scripts
> and library files supplied as input to or produced as output from the
> programs of this Package do not automatically fall under the copyright
> of this Package, but belong to whomever generated them, and may be sold
> commercially, and may be aggregated with this Package."  That means if
> you only use Perl/Artistic modules you shouldn't have to be under the GPL.

Yes, under the terms of the Artistic License, simply using a module or
the Perl interpreter itself doesn't make your program subject to the
terms of the Artistic License. (And the dual license means you can
choose between the Artistic terms and GPL terms, not that you have to
obey all the terms of both licenses.)

So, it's fine to create a BSD licensed piece of software written in Perl
and using Perl modules (check the license of the Perl modules, but most
of them are "the same terms as Perl" or pure Artistic).

Allison

[Alex Hanson]

On 07/12/07 20:16, Allison Randal wrote:

> Matthew Flaschen wrote:
>> Alex wrote:
>>> I am writing a piece of software that I want to license as BSD. I am
>>> using Perl, which is licensed under both the GPL and its own Artistic
>>> License.
>>
>>> what about the modules included with Perl? Could a statement as
>>> simple as "use Carp"
>>> force my program to be licensed under the GPL?
>>
>> I believe most of the modules included in Perl use Artistic/GPL.
>> Artistic is explicitly not a copyleft license, and says, "The scripts
>> and library files supplied as input to or produced as output from the
>> programs of this Package do not automatically fall under the copyright
>> of this Package, but belong to whomever generated them, and may be sold
>> commercially, and may be aggregated with this Package."  That means if
>> you only use Perl/Artistic modules you shouldn't have to be under the
>> GPL.
>
> Yes, under the terms of the Artistic License, simply using a module or
> the Perl interpreter itself doesn't make your program subject to the
> terms of the Artistic License. (And the dual license means you can
> choose between the Artistic terms and GPL terms, not that you have to
> obey all the terms of both licenses.)
>
> So, it's fine to create a BSD licensed piece of software written in
> Perl and using Perl modules (check the license of the Perl modules,
> but most of them are "the same terms as Perl" or pure Artistic).
>
> Allison
>

Thanks a lot for your help everyone. I wasn't quite sure how the dual
licenses worked, but I guess in my case I just take the most liberal
(i.e., BSD-like) clause and follow that.

-Alex Hanson

[Matthew Flaschen]

Alex wrote:

> Thanks a lot for your help everyone. I wasn't quite sure how the dual
> licenses worked, but I guess in my case I just take the most liberal
> (i.e., BSD-like) clause and follow that.

To be clear, you can pick a license, but can't really pick and choose
individual clauses.  In your case, you should choose the Artistic
/license/, which will allow what you want.

Matt Flaschen

[Philippe Verdy]

Matthew Flaschen wrote:
> Alex wrote:
> I believe most of the modules included in Perl use Artistic/GPL.
> Artistic is explicitly not a copyleft license, and says, "The scripts
> and library files supplied as input to or produced as output from the
> programs of this Package do not automatically fall under the copyright
> of this Package, but belong to whomever generated them, and may be sold
> commercially, and may be aggregated with this Package."  That means if
> you only use Perl/Artistic modules you shouldn't have to be under the GPL.

Look into the GPL, and you'll see that it does not automatically assigns the
GPL licence to the data that is fed into or produced by the GPL program, if
this data itself is not licenced by the GPL, and if the output does not
contain significant parts of data that can be derived directly from the GPL
program alone, but only from the data provided by the user of the program
and not by the GPL copyright holder.

Users can then use GPL programs with their own private data, and
redistribute the result produced without being bound to the GPL licence.

Otherwise, you could not even legally play a copyrighted music file using a
GPL-licenced media player...

You could not browse most of the web (implicitly copyrighted even if there's
no explicit licence or licencing terms saying it) with a GPL-licenced
browser.

You could not use a GPL-covered document processor to print a copyrighted
book.

You could not publish copyrighted research papers using a GPL-covered TeX
processor.

You could not publish a copyrighted web site using a GPL-covered web server.

You could not download a copyrighted file using a GPL-covered FTP client...

(and all this is independent of the type of licence that covers the input
data: the copyright on this data is not automatically reassigned, its
licence is not altered in the output, unless the output is a derived work
covered by the GPL of the program with the help of which you have generated
it.)

[Matthew Flaschen]

Philippe Verdy wrote:
> Look into the GPL, and you'll see that it does not automatically assigns the
> GPL licence to the data that is fed into or produced by the GPL program,

I have read the GPL, and am well aware of that.

> if this data itself is not licenced by the GPL, and if the output does not
> contain significant parts of data that can be derived directly from the GPL

This is essentially why a Perl program that uses GNU Readline is (in the
FSF's view at least) derived from it.

> Users can then use GPL programs with their own private data, and
> redistribute the result produced without being bound to the GPL licence.

Generally true.

> Otherwise, you could not even legally play a copyrighted music file using a
> GPL-licenced media player...

GPL software is copyrighted.  But of course you can play proprietary
media in a GPL player.  That is not the same thing as linking a
proprietary program to a GPL library.

> [snip examples]

> (and all this is independent of the type of licence that covers the input
> data: the copyright on this data is not automatically reassigned, its

The GPL never reassigns copyright; it couldn't, and doesn't try.
Anyway, I'm aware none of those examples require the output to be GPL.
A GPL Perl module is a significantly different case.

Matt Flaschen

[David Woolley (E.L)]

[ off topic: not related to the approval of a new licence ]

Philippe Verdy wrote:

> Otherwise, you could not even legally play a copyrighted music file using a
> GPL-licenced media player...

The GPL does not restrict the creation of private derivatives, so,
whilst there would be no GPL violation in providing a public performance
  either (although almost certainly a violation of the copyright on the
music file) playing the music in private is not validly comparable with
the question at issue.
--
David Woolley
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