
Qt Online Installer 3.2.3 - caution
https://www.qt.io/blog/qt-online-installer-3.2.3-released
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Nokinside
If you want to use Qt in commercial closed source product without paying for
the license, it’s easy to do when you use LGPL version.

1\. Do not buy the commercial version.

2\. Do not change the source code of the Qt library. Use it at it is.

3\. Provide access to either statically or dynamically linked object files
with instructions for linking. Static vs. dynamic linking does not matter with
LGPL. LGPL requires access to source code and the ability for the user to
modify open source library and link it to your closed source object file to
create binary.

You compile your commercial code into commercial.o then compile LGPL code into
lgpl.o and link them into a single binary.

    
    
        ld -o binary  lgpl.o commercial.o -lc
    

When you deliver the software, you send the binary, provide access to
commercial.o and LGPL licensed source code with instructions for linking. User
has now the ability to meddle with LGPL version of Qt, compile it into lgpl.o
and link it against your commercial.o without having access to your source
code.

(note: of course you can modify the Qt under LGPL when you release
modifications with the LGPL. But then you have to maintain the fork on your
own and you don't usually want to do that.)

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abjKT26nO8
That's the equivalent of creative accounting for software developers.

Dick move.

Such behaviour just leaves the market to big corps who can afford to release
such tools for free while extracting money from elsewhere.

~~~
pabs3
The above technique is compliant with the license of Qt (LGPL). If Qt didn't
want to allow it, they would have used a different license like the GPL.

~~~
abjKT26nO8
Then you wouldn't be able to write BSD-licensed apps using Qt at all. Creative
accounting is also legal per se. It doesn't make it right.

~~~
Nokinside
Why not?

There's nothing in the BSD license that prevents you from mixing in code. LGPL
doesn't care if you link it against BSD code. Just that the LGPL code must
stay under LGPL.

~~~
abjKT26nO8
I was replying to the suggestion that Qt could be released under GPL if its
authors wanted to prevent the creative accounting described by OP.

Also, LGPL is already problematic, because you cannot link statically with it.

~~~
Nokinside
> Also, LGPL is already problematic, because you cannot link statically with
> it.

Damn. I just wrote the whole top level comment to explain that you can link
statically LGPL code and how to do it with details.

~~~
abjKT26nO8
That's just a workaround. Now I need to add *.o files to my deb packages. Or
ship source code in deb packages? What is it? Gentoo?

~~~
rcxdude
You don't, you just need to provide a way to get them (you can even specify
that requests must be sent by post and charge postage for the response on a
CD). It's not a 'workaround', it's literally how the license is supposed to
work.

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t0astbread
Slightly off-topic but it's interesting how all of the discussion on this post
(right now) is centered around the only other top-level comment rather than
the article.

