Is inherited class a derivative work?

David Johnson david at
Wed Oct 17 03:34:17 UTC 2001

On Tuesday 16 October 2001 03:22 pm, Michael Beck wrote:

> I just got a response from FSF lawyers stating that "inheritance is
> considered modifying the library" (see below). My question was related to
> releasing code under LGPL and wanted to make sure that I've interpreted
> correctly the difference between "work based on a library" and "work using
> a library", and according to FSF, inheritance falls under "work based on a
> library" and as such should be released under LGPL.

Now that's a truly scary thought if you think about it. The KDE core 
libraries are under the LGPL, but there are many KDE applications that are 
under different licenses and which of subclassed some KDE classes (kwin, 
kicker, cervisia, etc). Are these programs all now illegal? Will we have 
another KDE boycott by Debian and Redhat?

I'm going to have to check that nothing in my C++ inheritance chain is LGPL.

David Johnson
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