Subj : Re: GNU Public Licences Revisited (again)
To   : comp.programming
From : Arthur J. O'Dwyer
Date : Tue Aug 23 2005 12:47 pm


On Tue, 23 Aug 2005 gswork@mailcity.com wrote:
[...]
> hmm, well just drifting through my thoughts on what you said based
> around a hypothetical commercial closed source app...

   See my post in reply to Joe's. But here are the parts relevant to your 
thoughts:

> I'd have thought that if you use a gpl library, for instance, and used
> it unmodified you'd just say so, and maybe produce the code on request
> (or just point to the project that produced it).

   That's okay, as long as the project that produced it sticks around. If 
they go under, then it's your responsibility to distribute the source on 
request.

>   If you used a
> library and altered it then you would be obliged to make your
> modifications open source too.

   Yes.

> I'm not sure if the entire application which calls the library needs to
> be made open source, that's sounds unrealistic because it is the
> library source that's been used and altered not the rest of the app.

   Writing a bunch of extra code that calls the library /is/ altering the 
library, from the literal-minded CS point of view. You're taking one 
collection of source code and turning it into another, different 
collection that includes a lot of the original. That makes it a derivative 
work, copyrightically speaking. If the library was GPL'd, the resulting 
work must be GPL'd. If the library was LGPL'd, the resulting work doesn't 
need to be GPL'd, although it can be, of course.

> Imagine the consequence of using a tiny open source compression library
> inside an enormous application just to compress some data and having to
> turn over the whole app because of it, no one making a closed source
> app would bother with it.

   Exactly! Now you're seeing the light!  If it becomes so infeasible to 
create closed-source compressors that nobody does it, then the field of 
compression technology will suddenly have become completely free and open, 
thus benefiting everybody. Remember, locked is bad. Unlocked is good.

> now if you just took the entire source to Abiword, for instance, and
> changed that around a bit to produce a variant then you would need to
> release source for the whole, it being a derivative of abiword.

   Assuming you released the derivative as a binary, yes. Of course, since 
AbiWord is free software, you can do whatever you want with it on your 
/own/ time. (Unlike Microsoft Word, where even /making/ a derivative is 
cause for a lawsuit. This is perhaps the coolest difference between GPL 
and closed-source licenses.)

> Those are just some thoughts anyway - the actual terms of the license
> are what matter.
>
> what i would add is that it must be nearly impossible to police,
> especially in gray areas - let's say you produce a nice word processor
> which borrowed heavily from Abiword but was actually significantly
> different - it may fall under the gpl and you may be obliged to release
> to whole or part of what you've done, but who is going to really know
> or be able to tell except you?

   The judge, when the maker of AbiWord decides to actually /enforce/ the 
GPL. ;-)

-Arthur,
four freedoms

.