PyQT Licensing and plugins/scripting

[Fabio]

Hi all,
I'm about to write an application, and I'd like to use PyQt, but before
choosing this toolkit I would like to clarify some particular licensing
issues; if some user has already touched these, I would like to hear from
his experiences.

This app should be cross-platform, so, given qt licensing policies, I would
buy a commercial PyQt license and a commercial Qt license.

Could I license the application under the GPL for Gnu/Linux and under a
commercial license for Windows and Mac OS X? If this is possible, I guess
that contributions to the GPLed version could not be incorporated in the
commercial version, but this would not be a big problem.

The main issue with licensing is that I would like to give users of the
application a scripting framework (for macros and the like), and eventually
a plugin framework; PyQT redistribution policy states that if an user can
get in touch with PyQT directly it should have a commercial license itself;
how does this apply to those who want to develop commercial PyQT
applications with a plugin/scripting framework?

Thanks,
Fabio

 

[Jarek Zgoda]

I'm about to write an application, and I'd like to use PyQt, but before
choosing this toolkit I would like to clarify some particular licensing
issues; if some user has already touched these, I would like to hear from
his experiences.

This app should be cross-platform, so, given qt licensing policies, I would
buy a commercial PyQt license and a commercial Qt license.

Could I license the application under the GPL for Gnu/Linux and under a
commercial license for Windows and Mac OS X? If this is possible, I guess
that contributions to the GPLed version could not be incorporated in the
commercial version, but this would not be a big problem.
Right.

The main issue with licensing is that I would like to give users of the
application a scripting framework (for macros and the like), and eventually
a plugin framework; PyQT redistribution policy states that if an user can
get in touch with PyQT directly it should have a commercial license itself;
how does this apply to those who want to develop commercial PyQT
applications with a plugin/scripting framework?

This is vague, what one considers "get in touch"? If you perform any
calculations and display results to the user, would it be "get in touch
with PyQt"? I think not. If showing a window depends on your user's
scripting code, then I thing it's "get in touch", but if you simply show
a window with display widget (more or less advanced, be it QTextView or
even sort of grid) with results, this doesn't cover the case, as PyQt is
only used for display purposes -- just as with any other use of PyQt.

 

[Kevin Walzer]

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PyQt on OS X is also available under a GPL version. I have a binary
installer available at http://www.wordtech-software.com/pyqt-mac.html



Fabio wrote:

| Hi all,
| I'm about to write an application, and I'd like to use PyQt, but before
| choosing this toolkit I would like to clarify some particular licensing
| issues; if some user has already touched these, I would like to hear from
| his experiences.
|
| This app should be cross-platform, so, given qt licensing policies, I
would
| buy a commercial PyQt license and a commercial Qt license.
|
| Could I license the application under the GPL for Gnu/Linux and under a
| commercial license for Windows and Mac OS X? If this is possible, I guess
| that contributions to the GPLed version could not be incorporated in the
| commercial version, but this would not be a big problem.
|
| The main issue with licensing is that I would like to give users of the
| application a scripting framework (for macros and the like), and
eventually
| a plugin framework; PyQT redistribution policy states that if an user can
| get in touch with PyQT directly it should have a commercial license
itself;
| how does this apply to those who want to develop commercial PyQT
| applications with a plugin/scripting framework?
|
| Thanks,
| Fabio

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[Phil Thompson]

Hi all,
I'm about to write an application, and I'd like to use PyQt, but before
choosing this toolkit I would like to clarify some particular licensing
issues; if some user has already touched these, I would like to hear from
his experiences.

This app should be cross-platform, so, given qt licensing policies, I would
buy a commercial PyQt license and a commercial Qt license.

Could I license the application under the GPL for Gnu/Linux and under a
commercial license for Windows and Mac OS X?

As there is are GPL versions of Qt and PyQt for Mac OS X, it's only Windows
you need to handle differently.

If this is possible, I guess
that contributions to the GPLed version could not be incorporated in the
commercial version, but this would not be a big problem.

"Minor" contributions you don't need to worry about. I think that the GPL FAQ
covers what is considered "minor". For significant contributions you would
need to get the agreement of the contributors beforehand. Some projects state
that contributions will only be accepted if the copyright of those
contributions are transferred to the main project author.

The main issue with licensing is that I would like to give users of the
application a scripting framework (for macros and the like), and eventually
a plugin framework; PyQT redistribution policy states that if an user can
get in touch with PyQT directly it should have a commercial license itself;
how does this apply to those who want to develop commercial PyQT
applications with a plugin/scripting framework?

The key is access to the Qt API. If your applications gives the users access
to the API then those users are developers and need their own licenses. On
the other hand if the API is sufficiently removed from the Qt API then you
shouldn't have a problem. Your API should restrict itself to extending the
capabilities of your application - the more general purpose you make it, the
more you risk a visit from the lawyers.

Phil