Question regarding modules/pluggins license?

[Chris F Clark]

Larry Masters asked:

> I currently work on an open source project that uses the GPL for a 
> license. The project is written in PHP and uses modules/pluggins. The 
> project has an API  that other developers can use to create these 
> modules/pluggins so they work within the framework of the project. 

If you (the author of such a project) clearly intend for the
modules/pluggins to be not constrained by your license, then you
should use a license that specifically allows it (or otherwise
indicate that the intent is to specifically allow that case).  (Of
course, if you are one of several authors, as a group you will have to
come to a consensus on this topic).

The Lesser GPL is a license that attempts to make such things clear
(and still be as closes as possible to the GPL).  It may also be
possible to express your intentions in additional clauses in either
the source code or documentation.  The "standard" C++ libraries
shipped with g++ appear to do this in comments in their header files.
Somewhere it is expressed that simply using the Linux API does not
cause programs running on Linux to be GPL even though many parts of
Linux are GPL (and I presume the whole thing is).

In any case, being explicit is a good thing.  So, is being careful.

The worst case I can imagine (for me as a potential end user) is that
someone develops some code licenses it under the GPL (and intends for
that to be viral to all software which links to it), that code gets
integrated (by a third party) into some package that I wish to use
which purportedly allows linking (of modules/pluggins) without viral
license attachment (thus potentially contravening the original authors
copyright) and I as a user link the software with code (a module or
pluggin) I cannot ship under the GPL and ship the resulting package
(making the contravention real).  The original author now sues someone
(probably me) for doing something I thought I was permitted to do.  No
one is happy!

Best regards,
-Chris
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