[PyQt] A nasty licencing question

Kyle Altendorf sda at fstab.net
Mon Jul 30 16:26:44 BST 2018

On 2018-07-30 09:19, Sampsa Riikonen wrote:
> On 30.07.2018 13:47, David Boddie wrote:
>> On Mon Jul 30 10:23:50 BST 2018, Sampsa Riikonen wrote:
>>> On 30.07.2018 12:16, David Boddie wrote:
>>>> How does apply to the scripts you were talking about? Sure, the 
>>>> combined
>>>> work is now licensed under the GPL but the original scripts can 
>>>> still be
>>>> obtained from outside the combined work and are still MIT licensed.
>> I was being a bit careless with words. I meant "snippets" rather than
>> "scripts", but your questions below are still valid. In my mind they 
>> are
>> different things, but that's not important here. :-)
>>> What do you mean David..?
>>> Do you mean if you remove "from PyQt5 import .." then that's "outside
>>> combined work" and thus is not anymore GPL licensed?
>> No, if you obtain something licensed under the GPL then changing the 
>> module
>> dependencies isn't going to change its license.
> So, if at a certain moment, you don't have the PyQt license and add the
> following line into your code:
> from PyQt import ...
> Then that's it.  Your code will be forever GPL .. it became GPL at the
> very moment you distributed it (uploaded to the internet).  You can't
> use it anymore in any other context that GPL.  Even removing those
> damning lines wont save it.

The author can make new code (even based on their existing code) and 
release it under another license.  In fact, Qt and PyQt both do this 
without even making changes.  But sure, when you go to distribute it you 
ought to do so under an appropriate license for the code.  Making use of 
(free) PyQt in the code would mean you should license it as GPL.

It sounds like the (maybe) simple solution though is to use PySide2 so 
that you can license your code any way you want (presumably at least a 
GPL compatible license, to meet your goals).  If someone wants to use 
(free) PyQt, they can make the change and deal with the GPL licensing 
concerns of what they distribute.  Or, get a lawyer and analyze each 
'snippet'/script to see if it falls under the referenced 'fair use' 


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