[License-discuss] Shortest copyleft licence

[Ben Tilly]

What does copyleft mean?

The purpose of a copyleft provision in my mind is to make it so that
changes get contributed back.  While it is clear that the Sleepycat
license attempts to do so, it does not stop source being available for
a nominal fee under an additional copyright license chosen by the
contributor.  If that license happens to be the GPL, well OK.  But
Sleepycat can't use that code without changing their license.  If that
license happens to be something preventing further modification and
redistribution, then you've lost the whole point of copyleft.

Nailing down copyleft and making it actually work is surprisingly
tricky.  That is one reason why careful copyleft licenses are so
verbose.

On Mon, Mar 30, 2015 at 7:24 AM,  <cowan at ccil.org> wrote:
> Maxthon Chan scripsit:
>
>> Is it favorable to add a copy left clause into 2BSDL to make it copyleft?
>> "You must provide the source code, in its human-preferred format, with
>> this work or any derivatives of this work you created when
>> redistributing."
>
> That's pretty much what the Sleepycat license does.  Here's a very lightly
> edited version of its additional clause:
>
>     Redistributions in any form must be accompanied by information
>     on how to obtain complete source code for the licensed software
>     and any accompanying software that uses the licensed software.
>     The source code must either be included in the distribution
>     or be available for no more than the cost of distribution
>     plus a nominal fee, and must be freely redistributable under
>     reasonable conditions. For an executable file, complete source
>     code means the source code for all modules it contains.
>     It does not include source code for modules or files that
>     typically accompany the major components of the operating
>     system on which the executable file runs.
>
> The restrictions pretty much match those of the GPL2.
> The Sleepycat license itself is redundant and non-templatized,
> so it can't be reused directly.  If someone felt like
> proposing something like 2-clause BSD + the above, I for one would
> welcome it.  Unlike the GPL, this does not create a new and
> distinct software commons.
>
> --
> John Cowan          http://www.ccil.org/~cowan        cowan at ccil.org
> Police in many lands are now complaining that local arrestees are insisting
> on having their Miranda rights read to them, just like perps in American TV
> cop shows.  When it's explained to them that they are in a different country,
> where those rights do not exist, they become outraged.  --Neal Stephenson
>
>
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