[Twisted-Python] Twisted & Qt

James Y Knight foom at fuhm.net
Tue Sep 26 11:42:18 EDT 2006

On Sep 26, 2006, at 9:45 AM, glyph at divmod.com wrote:
> I've gotten in touch with Riverbank Computing, the copyright  
> holders on PyQt, and they are of the opinion that any Python code  
> that imports "qt" is, in fact, a derivative work and therefore  
> beholden to the GPL.

The only issue here is that we don't want to confuse people by having  
part of Twisted (qtreactor) be GPL.

But wait, the MIT license is compatible with the GPL. It is perfectly  
acceptable to write a work under the MIT license (qtreactor) which  
links to a GPLd work (pyqt). I've never seen anybody say that's  
illegal. The only issue here is that you cannot write a proprietary  
program using qtreactor (even though qtreactor itself is MIT),  
because pyqt is still licensed under the GPL, and anything linking  
with the GPL program must be *GPL-compatible*. But even though you  
cannot take advantage of all the permissions of the MIT license when  
using qtreactor, our code, itself, is not under the GPL. You could  
take the qtreactor, make a derivative of it which doesn't use qt, and  
have that be MIT. I really think there's no problem here.

> I'll be removing it from the Twisted repository and contributing it  
> to Riverbank for inclusion in PyQt at my next available  
> opportunity.  This is probably going to require an immediate  
> addition of a plugin API for reactors, so it can be loaded externally.

I strongly object to this, regardless of the outcome of the above.  
The internal reactor supporting APIs (posixbase etc) are not stable  
enough that I'm at all comfortable with giving a reactor over to  
external maintenance. If we have to, please instead let's segment it  
into a separate distributable, but still develop and release it in  
lockstep with twisted core.


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