I say this [that using the readline API makes your code GPL too]
based on discussions I had with our lawyer long ago. The issue
first arose when NeXT proposed to distribute a modified GCC in two
parts and let the user link them. Jobs asked me whether this was
lawful. It seemed to me at the time that it was, following
reasoning like what you are using; but since the result was very
undesirable for free software, I said I would have to ask the
lawyer.
What the lawyer said surprised me; he said that judges would
consider such schemes to be "subterfuges" and would be very harsh
toward them. He said a judge would ask whether it is "really" one
program, rather than how it is labeled.
However, as pointed out by others this doesn't appear to be a case of using a public GPL API at all, but rather case of code being copied. See http://drewblas.com/2010/07/15/an-analysis-of-gpled-code-in-... specifically this comparison: http://drewblas.files.wordpress.com/2010/07/diff.png
It's clearly the case that both Wordpress and the FSF believe that programs which link or include GPL-ed works are derivative works. Even if they're wrong, isn't it somewhat unethical to agree to an agreement and then violate what the other side of that agreement have told you from the beginning they believed it means?
The way it works is by overriding the behavior of WordPress, both integrating in internal filtering of input/output, reacting on actions/events, integrate with the admin interface of WP and calling APIs.
If this is not a derivate work, nothing is.
That said, maybe Wordpress themes are much different than normal themes, and are much more tightly coupled? That WP would pursue this if not puzzles me.
They can be made to be tightly coupled, but they're not necessarily intended to be. A lot of themes override core WordPress functions via a functions.php in the theme root directory. You don't have to include any core WP code in your theme, but WP provides an easy way to do it if you need to.
That WP would pursue this if not puzzles me.
IMHO, Mullenweg comes off looking like a brat in this whole mess. Regardless of the legality of the whole thing, this seems to be a straddling-the-line kind of situation, which makes it feel like there's some kind of ulterior motive at play.
Edit: This link from elsewhere in the thread totally changed my opinion. http://drewblas.com/2010/07/15/an-analysis-of-gpled-code-in-... Seems like Thesis should pretty clearly be GPL.
I feel like interpreted code is pretty hard to make derivatives of, honestly, though it seems like a fairly large number of people agree with you on this one.
Well, because there is WP PHP code in it. Once you do that you become a "derivative" and you take the license.
A theme is not beholden to the software's license. However, Thesis is more than just a theme.
Thesis integrates with Wordpress, it is not derivative from it. Same way Linux modules integrate with the Linux kernel (and many of them are closed source).
If someone is using a public/open API, and not distributing any part of the software, it means they are not based on the other.
See for instance: http://www.oreillynet.com/linux/blog/2006/08/why_binaryonly_...
At what point does dynamic linking make something a derived work - and how is dynamic linking fundamentally different, than, say, a remote procedure call (or SOAP or REST or whatever) over a network? The interface is different, but the principle is the same.
Also - the GPL does state that it's okay to link against things that are "standard parts" of the target system....
http://drewblas.com/2010/07/15/an-analysis-of-gpled-code-in-...
