Friday, August 28, 2009

The GPL and scripting languages

I was recently asked by an associate about how the GPL and LGPL impacts scripting languages. The short answer is that it's not clear.

My general take on the LGPL and scripting languages is that if one cut-and-pastes LGPL code A into code B, then code B falls under the LGPL. However if one script-includes code A into code B in the only real mechanism scripting languages allow then code B does not fall under the LGPL.

php: include 'Foo.php';
perl: require Foo::Bar;
python: import Foo
ruby: require "foo"
javascript: <script type="text/javascript" src="external.js"></script>

This differs from the application of the LGPL to compiled languages like C/C++ as the programmer decides how the machine code is combined: static versus dynamically linked. In Java if one has an LGPL jar file, the the code can be used in the standard way. If your code is combined with the contents of the LGPL jar file in a new jar, then your code falls into the LGPL.

What does the scripting language really do under the hood? It's different in each language. Some may physically include the file and parse-interpret it as one block of code, others may parse-interpret separately and resolve references between them much like a dynamic linker. Do the details matter? Unknown, yet one could reasonably assume the author of a piece of script code under the LGPL must have intended others to make script-include style uses OK. If in doubt check with the author and save that email.

What about the GPL? More clear.. no mixing of any kind can be done. One could argue that interpreted script is not linked in the way that compiled languages are... yet conservatively this is a "thin reed" to stand on.

What does this mean about the myriad of GPL javascript out there intermingling with non-GPL and proprietary javascript within browsers visiting script heavy websites everywhere? It's a dog's breakfast of legal issues.

The post Twenty questions about the GPL is pretty informative of the issues, worth a read... deeper than the above.

Posted via email from nealrichter's posterous

No comments: