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woogie

Member

From: Ottawa, ON

Registered: 2005-04-01

Posts: 45

Licenses .... *groan* [solution which could be wrong found]

OK, here's the deal:

Eclipse is licensed under the EPL, along with SWT and all its assorted baggage. I'm looking to write a plugin, and I'm a strong fan of the GPL for software. However, the FSF site lists the EPL as being GPL incompatible because of its patent clauses. Now, writing GPLed software lets me interact with GPL incompatible software through "customary means" - which would be the interfaces Eclipse opens up to plugins, through extension points. However, while reading up on the FSF GPL FAQ, I stumbled across a section on Java, and the concern was over subclassing.

From what I understand, my GPL code can't extend GPL-incompatible code, because I'm then creating a derivative work (not just using the library). See http://www.gnu.org/licenses/gpl-faq.html#TOCOOPLang This would mean for my plugin, I couldn't do anything like extending the SWT Adapters and other convenience classes.

So then I turn around and look at the EPL http://www.eclipse.org/legal/epl-v10.html, and it seems like I can license my own self-contained programs however I want to. But then this whole extending problem rears its head again. When I subclass parts of SWT (as the design intends!), that means I'm creating a derivative work. Which then has to be covered under the EPL as the EPL doesn't exempt "derivative works".

So then I turn to the web, and lo and behold I find a bunch of GPL licensed Eclipse plugins, using SWT. Are people just ignoring the language of the licenses and licensing their code however they please, or am I being too cautious with respect to the "derivative work" issue?

woogie

Member

From: Ottawa, ON

Registered: 2005-04-01

Posts: 45

Re: Licenses .... *groan* [solution which could be wrong found]

To answer my own question:

The helpful, helpful people who wrote the EPL FAQ decline to give any details on what constitutes being a derivative work of Eclipse. So I'll just fly by the seat of my pants and arbitrarily declare that using SWT and registering with Eclipse, and extending parts of SWT doesn't constitute making a derivative work  (seriously, the FAQ for the EPL talks about what constitutes a derivative work by throwing up the text of USA copyright law and saying "go hire a lawyer". Thanks guys)

So that means that I can then license my plugin as GPL, as long as every file of mine which touches an Eclipse library carries a copyright exemption that allows it to be "linked" with EPL licensed software. Linked, in this case, meaning I made what the FSF would define as a derivative work, *if* the initial work was covered by the GPL. Since the initial work is under the EPL, and I've got no clue wrt to the EPL, I'm calling it not a derivative.

/Who's up for a five minute hate on ESR? *grumble, mutter*