When to evaluate dual licenses

[Chuck Swiger]

On Dec 13, 2007, at 3:14 PM, Matthew Flaschen wrote:
>> The section about "limiting its use to free programs"; the complete
>> paragraph is:
>>
>> "However, when a library provides a significant unique capability,  
>> like
>> GNU Readline, that's a horse of a different color. The Readline  
>> library
>> implements input editing and history for interactive programs, and
>> that's a facility not generally available elsewhere. Releasing it  
>> under
>> the GPL and limiting its use to free programs gives our community a  
>> real
>> boost. At least one application program is free software today
>> specifically because that was necessary for using Readline."
>
> It doesn't say that program used it optionally.

True.  As we've discussed previously, it also doesn't mention that a  
BSD-licensed readline with a compatible API exists, or that there also  
is a BSD-licensed libedit which offers similar functionality (via a  
different API), which predates GNU readline:

   http://www.crynwr.com/cgi-bin/ezmlm-cgi?3:mss:12220:200701:eekjfkiiplhjdkoabfid

In particular, the USAGE file for GNU readline states:

> From: Richard Stallman <rms at gnu.org>
> To: chet at nike.ins.cwru.edu
> Subject: Use of Readline
> Reply-to: rms at gnu.org
>
> I think Allbery's suggestion is a good one.  So please add this text
> in a suitable place.  Please don't put it in the GPL itself; that
> should be the same as the GPL everywhere else.  Putting it in the
> README and/or the documentation would be a good idea.
>
> ======================================================================
> Our position on the use of Readline through a shared-library linking
> mechanism is that there is no legal difference between shared-library
> linking and static linking--either kind of linking combines various
> modules into a single larger work.  The conditions for using Readline
> in a larger work are stated in section 3 of the GNU GPL.

-- 
-Chuck