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Comment by justaaron | Hacker News Reader

Just to be clear, QT still has the same licensing, correct? dual:LGPL or commercial

commercial license costs + not redistributable (example, if included in a BSD or MIT library/framework/tool...)

or LGPL (also requires project to be LGPL)

just checking, as it's a factor in why Qt is not universal, but only ubiquitous, which is still a good thing, because "diversity" and not wanting to put the fate of all gui forever into the hands of one entity etc..

but: any other declarative (like qml) gui frameworks out there in Linux land?

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Note that some modules are not available under the LGPL. You don't get charts, data visualisation or any of the embedded tooling.

LGPL does not require the project to be LGPL. It simply means that you must provide users means to link your program to a version of Qt that they've compiled, or you provide the source of the Qt distribution that you compiled to build your application. You can have a commercial, closed-source, application using LGPL Qt.

"A program that contains no derivative of any portion of the Library, but is designed to work with the Library by being compiled or linked with it, is called a "work that uses the Library". Such a work, in isolation, is not a derivative work of the Library, and therefore falls outside the scope of this License."

Contrary to popular belief you can even statically link an LGPL library and remain closed source, but you may need to distribute your object files so that someone can statically link a different library version with your code.

I'm not sure what happens if you modify Qt in some way though, presumably you're still covered if you release the modifications you made.

Full answer here: http://answers.google.com/answers/threadview/id/439136.html

I'm pretty sure Chart, DataViz, etc are now available in the open source edition.

Yes, under GPLv3[1], though that may be unpleasant to people who wanted to use only LGPL-licensed Qt.

1: https://doc.qt.io/qt-5/qtmodules.html#gpl-licensed-addons

Not LGPL though.

For charting, Qwt is a pretty mature library now. The documentation is somewhat sparse, but complete if you look at the Doxygen + examples as well. The author is active on the Qt forums too.

If you provide a version that can be dynamically linked against a users' self-compiled QT version, can you release a statically compiled version alongside it and still be compatible with the license?

> If you provide a version that can be dynamically linked against a users' self-compiled QT version, can you release a statically compiled version alongside it and still be compatible with the license?

you can release a statically linked version and share your compiled proprietary object files (+ build instructions) ; that's enough to comply with LGPLv3

> or LGPL (also requires project to be LGPL)

This is not correct. LGPL only requires that Qt is linked as shared libraries and sources of any changes to the Qt itself is provided.

> but: any other declarative (like qml) gui frameworks out there in Linux land?

I don't see how the license is a problem. It used to be not 100% open source but it is now, and it has a commercial license if you don't want to open source your program. You can also dynamically link to LGPL versions of the library from your program. [1]

In any case, to answer the question, you have guile gnome [2] which sort of does the same thing but in a scheme language.

[1] https://softwareengineering.stackexchange.com/questions/8614...

[2] https://www.gnu.org/software/guile-gnome/

You can distribute closed source product in Qt without buying commercial license. LGPL allows this.

You have to either

1) dynamically link to QT libraries, or

2) provide object files that can be statically linked against LGPL libraries.

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