Does a GPL API infect its apps?

Ross N. Williams ross at
Thu Oct 21 07:57:31 UTC 1999

At 10:57 PM -0700 20/10/99, Arandir wrote:
>On Wed, 20 Oct 1999, Ross N. Williams wrote:
>> I just want to point out that the use of the virus metaphor to describe
>> the legalities of association in relation to the GPL is inappropriate
>> because the "infection" does not proceed beyond one level.
>I'm not sure I follow you. If you have written a GPL library, and I create a
>library that links to it, then my library must be GPL as well.
>Anyone who links
>to my library must have their code be under the GPL as well. And so on. This
>goes further than one level. 

Half true. Your library can be released under several licences including
the GPL. That's how commercial vendors can release their code under the
GPL and sell the same code as commercial products.

   GPL 5. You are not required to accept this License, since you have not
   signed it.  However, nothing else grants you permission to modify or
   distribute the Program or its derivative works.

(but if something else DOES grant you permission... :-)

So, if X is under the GPL only and you want to link Y with it, you
need to release Y under the GPL. However, that doesn't stop you releasing
Y under other licences too. If you have also released Y under another
licence L, then Z can be linked with Y under L. Hence the GPL is not viral.

Correct me if I'm wrong.

Hey, maybe someone should invent a licence algebra :-)


Dr Ross N. Williams (ross at, +61 8 8232-6262 (fax-6264).
Director, Rocksoft Pty Ltd, Adelaide, Australia: 
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