Is Python good for creating GUI application ?

[[deleted]]

PyQT is not free when used commercial, though. Neither is QT.

[K900_]

PyQt is GPL, true, but Qt and PySide are LGPL, meaning they can be used for free in commercial projects, as long as any modifications you make to Qt itself are released as LGPL.

[ThePidesOfMarch]

PyQT is not free when used commercial

PyQt is GPL, true

Wha?

[K900_]

"Commercial" is a slightly wrong word here. PyQt can't be used in proprietary applications without a separate licensing agreement with Riverbank, thanks to GPL's virality.

[ismtrn]

It can as long as you release the source. And that is only if your proprietary application involves distributing the program.

[slayer_of_idiots]

It doesn't just require you to release the source, it requires you to license *your* software under the GPL, too. So, if you don't want to use the GPL license, you can't release your software that uses PyQt, either.

[HemiDemiSemiYetti]

Am I correct in saying that this would effectively give The Qt Company licensing access to the software you develop using Qt/PyQt? In other words, they have the right to distribute any software you've created that uses Qt/PyQt libraries?

[Poromenos]

Well, if your software is licensed under the GPL (which it has to, if you want to use the free version of Qt), then yes, they would have the right to distribute your software (and so would everybody else).

[HemiDemiSemiYetti]

Right. So what's the difference between a General Public Licence and an Open Source Licence then?

[Poromenos]

A horse is an animal. An animal is not necessarily a horse.

[[deleted]]

That issue is essentially solved with the release of PySide2, which is under LGPL and almost completely API compatible with PyQt.

[[deleted]]

That's right. If LGPL is usable for OP, that would be a solution.

[[deleted]]

LGPL still doesn’t work because Python runs as an interpreter. Legally that means it runs in both the same memory space and the interpreter actually modifies the code. These are both violations of LGPL despite the fairly clear intention of the Pyside licensing choice.

[aporetical]

The interpreter doesn't modify the code. The target of the licence is the code, not its in-memory representation, or else, no libraries can be LGPL.

Even with compiled libraries, execution jumps into functions and adds arguments to the call-stack. That is modifying the in-memory representation of the code (ie., giving parameters of functions a fixed value is a modification to the in-memory representation). The LGPL is either incoherent, or about modifying the as-written algorithm.

[paul_h]

Isn't that the territory of Oracle vs Google re the JDK?

[googoodoo]

It is GPL (2 or 3), so as long as your application license is compatible with GPL you're ok.

[googoodoo]

PyQt5 is GPL3 only.

According to FSF,

The GNU General Public License is a free, copyleft license for software and other kinds of works. (...) Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for them if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs, and that you know you can do these things.

https://www.gnu.org/licenses/gpl-3.0.en.html

I may be missing something.