Clarification on license for embedded/API use?

[Emanuele Aina]

John Labovitz ipotizzò:

> However, it does bring up the issue of licensing.  It seems Mercurial  
> is under a straight GPL license, which certainly makes sense for an  
> application.  However, it is problematic if I want to use its API in  
> a proprietary application (which mine is).  If the license was LGPL,  
> I think there'd be no question.  However, without Mercurial itself  
> being LGPL, does the GPL license carry through to the hosting (non- 
> GPL) application?

Yes. You should not be able to use Mercurial as a library in your 
application.

Unfortunately this restriction does apply even to programs with simply 
GPL-incompatible licenses, such as Eclipse or Apache.

As Mercurial is released under the GPLv2 even GPLv3 programs will be 
affected.

There is any hope that Mercurial will be relicensed to the LGPL? :)

> I think this is an issue regardless of whether there's an  
> intermediate like my Objective-C wrapper framework (which I plan to  
> publish under some free license, LGPL or otherwise) or the  
> Mercurial's Python API is used directly.

Yes. You can only use it from the command line (with pipes and whatnot) 
or writing a separate GPL-licensed daemon which listens for commands 
from your proprietary app.

> Or should I talk to the Selenic folks and negotiate a commercial  
> license?

That would work if Selenic was the only copyright holder.

Right now you would need to ask every Mercurial contributor to relicense 
his portion...

-- 
Buongiorno.
Complimenti per l'ottima scelta.