Re: [gtk-list] Re: Gtk & Qt



On Fri, 10 Jul 1998, Joel Becker wrote:

> Public Licensed, GNU Library Public Licensed, or a third GPL like
> statement (it's shorter).  What makes it different from the GPL is that
> you cannot sell it and you CANNOT modify Qt.  A GPL'd library can be
Which makes it incompatible with GPL/LGPL. Which doesn't matter perhaps
for your programs, but starts to matter if you want to use third party
code. We will see when KDE gets KDE gimp, gdb, emacs, etc.
(Probably after KDE switches away from Qt to Harmony, which is a piety, as
 Kimp the KDE gimp is already done. But it is not distributable, because
 of the Qt license.)
> modified, as long as you provide everything that is necessary.
> 	However, this is a moot point, cause you don't need to modify Qt
> to change its functionality.  It's C++.  You just extend the classes :-)
Since when can you extend classes in C++? ObjC can extend existing classes
with new methods. TOM can extend existing classes with methods, data
members and new super classes. Smalltalk can extend classes when I
remember right with new methods. (The members are declared in the subClass
message.)

C++ only supports deriving from classes which is not enough to take some
code and use it. Technically speaking there are some problems here, e.g.:
-) you need to change the behaviour of class X and all it's subclasses.
   In C++ you would need to subclass all subclasses.
-) you need to change the behaviour of class X, and class X is allocated
   somewhere in the library.
-) It makes clean design more difficult, because you cannot extend the
   library object as would be needed for code reuse, but have to kludge
   around.

> 	There are more details, I am sure, but for the home user, using
> only open-source software, the license usage of Qt and GTK+ are
> effectively identical.  I am using free software, writing free software,
> and charging noone.  Therefore I can use both legally.
Yes and no. You cannot take somebody else GPL app and port it Qt.
Basically speaking, backporting from Gnome to KDE would be illegal.
(The other way is also not too wise: It's just takes one core KDE
 developer who is bought, and changes his mind about the interpretation
 of the GPL license, and the whole of KDE looses it's license.)

Andreas



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