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PyQt, Qt, Windows and Linux

Alex Martelli aleax at aleax.it
Mon Nov 17 05:07:11 EST 2003 
Jim wrote:
   ...
> Edition but I think you just told me the opposite. If I buy the Personal
> Edition and use it to write my program, I won't have the capability to run
> that software on any other computer besides my own (personal to me) ...
> not even my wife's computer downstairs, i.e., so the runtime elements
> don't come with the Personal Edition - which makes it functionally
> different?

I think the difference is legal (contractual), not technical: you do not
have the _permission_ to copy runtime elements to other computers, even
though you may have the physical ability to do so.


> theKompany web page says the Business Edition is "for commercial use."
> From my understanding, commercial means of or relating to commerce and
> commerce is buying and selling products and I'm not selling anything. This

Qt (all the way from Trolltech) is peculiar that way: if you want to
distribute programs that run under Microsoft Windows, then you do need
a commercial license (there are other variants such as the "academic"
license, etc, but I don't think they apply here).  Presumably the concept
is that if people choose to pay for their operating systems, rather than
supporting free ones, they may well pay for applications too.

> is really confusing. I want to honor whatever licence I buy but it doesn't
> seem reasonable that I would have to pay $400 so I can give my own program
> away freely.

If you develop your Qt/PyQt applications with eric3 and distribute them
as free software (GPL) then you do not need to pay anybody anything.  If
you distribute applications otherwise than under GPL, or distribute
applications that run on Windows, then you do need to pay (purchase an
appropriate license -- unless your case can be covered by an academic
license or the like, I guess, but I don't know the details of that).

If you use Blackadder for the development, you can still give away your
sources (they are and remain your property); you just can't give away
executables and libraries that are not your property and that you are
not licensed to redistribute (such as those that come with Blackadder's
Personal edition/license).

Somebody's trying to develop a GPL version of Qt that runs under Windows
(with cygwin, specifically for the purpose of using KDE on cygwin); if
that effort matures (I don't know about its current status), then at
least C++-coded applications running on Windows+cygwin, covered by GPL,
and freely distributed, would become possible.  If and when this happens,
then for Python-coded applications to be distributable on the same terms
you will only need a suitable GPL-licensed PyQt (or PyQt with some license
that is at least GPL-compatible, of course).


Alex
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