[Twisted-Python] Twisted & Qt

Wilfredo Sánchez Vega wsanchez at wsanchez.net
Thu Oct 5 14:08:12 EDT 2006

   This is bunk.

   Any application that uses the GPL'ed Qt (or any other GPL noise)  
is subject to the terms of the GPL.  This, of course, includes the Qt  

   I'm find will pulling the reactor if you think it's creating  
confusion, but there are no circumstances under which the reactor  
itself must be licensed under the GPL.  It must be licensed under a  
GPL-compatible license in order to be used with Qt, and I agree that  
without that, the reactor is rather uninteresting in a practical sense.

   The Qt reactor can be MIT licensed, if for no other reason than  
the MIT license is GPL-compatible.  See "X11 License" here:


   The GPL is stupid.  There is no need to become stupid along with  
it.  The language below is misleading.  Instead say something like  
"If you use Qt in your application (which is likely, if you use this  
reactor), beware that you are subject to the license of Qt, which is,  
for some users, the GPL, which stupidly taints your code, and the  
reason people pay for Qt or use truly free software (like Twisted)  
instead."  Feel free to edit the pissy parts out.

   Anyway, short version: we don't redistribute GPL software, so we  
aren't bound to its terms, and neither is our software.  Any fool who  
does is.


On Sep 30, 2006, at 2:54 AM, glyph at divmod.com wrote:

> On Tue, 26 Sep 2006 14:14:24 -0400, glyph at divmod.com wrote:
>> On Tue, 26 Sep 2006 13:01:50 -0400, James Y Knight <foom at fuhm.net>  
>> wrote:
>>> If it is truly their position that the  textual source code of  
>>> qtreactor is a derivative work of PyQT, I  think they are quite  
>>> confused.
>> If it is your opinion that the "textual source code" is not a  
>> derivative work because it merely refers to, but does not  
>> incorporate, the text of qtreactor or qt, then the GPL is  
>> completely meaningless in the context of Python and there was no  
>> point in licensing it that way in the first place. Python bytecode  
>> does not make any additional references to the code it is  
>> importing beyond what Python source code does.
> I've got what I believe is the final word on this.  Phil Thompson  
> (again, Riverbank) says:
> """
> The reactor must be licensed under the GPL, but the rest of Twisted
> doesn't. A Twisted application that doesn't use the reactor can be
> licensed under the Twisted license. A Twisted application that uses  
> the
> reactor must be licensed under the GPL.
> """
> The best course of action, then, would be to distribute qtreactor  
> separately, since we can no longer say that Twisted is all MIT  
> licensed if we do not.  The practical ramifications of this are not  
> earth-shattering, so I think that we do not need to, e.g. release a  
> 2.4.1 which does not include qtreactor, but 2.5+ should definitely  
> not include it.
> I also asked specifically about not interfering with the PyQt/Qt  
> commercial license, and Mr. Thompson suggested wording like this:
> """
> This code is licensed under either the Twisted license or the GPL
> depending on the license of the copy of PyQt being used.
> If the GPL version of PyQt is being used then this code is also  
> licensed
> under the GPL. Given the viral nature of the GPL this means that any
> application must also be licensed under the GPL.
> If any other version of PyQt is being used (eg. commercial,  
> evaluation,
> educational) then this code is licensed under the Twisted license.
> """
> I suggest that we leave that wording mostly unchanged.
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