gnu readline licensing?

2010-04-20 Thread Brendan Miller
Python provides a GNU readline interface... since readline is a GPLv3
library, doesn't that make python subject to the GPL? I'm confused
because I thought python had a more BSD style license.

Also, I presume programs written with the readline interface would
still be subject to GPL... might want to put a warning about that in
the python library docs.
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Re: gnu readline licensing?

2010-04-20 Thread Robert Kern

On 4/20/10 1:09 PM, Brendan Miller wrote:

Python provides a GNU readline interface... since readline is a GPLv3
library, doesn't that make python subject to the GPL? I'm confused
because I thought python had a more BSD style license.


The PSF License is more BSD-styled, yes. The readline module can also be 
built against the API-compatible, BSD-licensed libedit library. Python's 
source distribution (even the readline module source) does not have to 
be subject to the GPL, though it should be (and is) GPL-compatible.



Also, I presume programs written with the readline interface would
still be subject to GPL... might want to put a warning about that in
the python library docs.


*When* someone builds a binary of the Python readline module against the 
GNU readline library, then that binary module is subject to the terms of 
the GPL. Any programs that distribute with and use that binary are also 
subject to the terms of the GPL (though it can have a non-GPL, 
GPL-compatible license like the PSF License). This only applies when 
they are combined with the GNU readline library, not before. The program 
must have a GPL-compatible license in order to be distributed that way. 
It can also be distributed independently of GNU readline under any license.


--
Robert Kern

I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though 
it had

 an underlying truth.
  -- Umberto Eco

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Re: gnu readline licensing?

2010-04-20 Thread Brendan Miller
On Tue, Apr 20, 2010 at 11:38 AM, Robert Kern robert.k...@gmail.com wrote:
 On 4/20/10 1:09 PM, Brendan Miller wrote:

 Python provides a GNU readline interface... since readline is a GPLv3
 library, doesn't that make python subject to the GPL? I'm confused
 because I thought python had a more BSD style license.

 The PSF License is more BSD-styled, yes. The readline module can also be
 built against the API-compatible, BSD-licensed libedit library. Python's
 source distribution (even the readline module source) does not have to be
 subject to the GPL, though it should be (and is) GPL-compatible.

 Also, I presume programs written with the readline interface would
 still be subject to GPL... might want to put a warning about that in
 the python library docs.

 *When* someone builds a binary of the Python readline module against the GNU
 readline library, then that binary module is subject to the terms of the
 GPL. Any programs that distribute with and use that binary are also subject
 to the terms of the GPL (though it can have a non-GPL, GPL-compatible
 license like the PSF License). This only applies when they are combined with
 the GNU readline library, not before. The program must have a GPL-compatible
 license in order to be distributed that way. It can also be distributed
 independently of GNU readline under any license.


Hmm... So if I ship python to a customer with proprietary software
that runs on top of it, then I need to be careful to disable
libreadline? Is there a configure flag for this or something?

Since libreadline is the default for Linux systems, and Python's
license advertises itself as not being copyleft, and being embeddable
and shippable... It would be nice if this were made clear. Maybe a
note here about libreadline: http://python.org/psf/license/

It seems to me that the whole of the python distribution would be GPL
after being built with libreadline, so this would be an easy trap to
fall into if you didn't realize that python used libreadline.
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Re: gnu readline licensing?

2010-04-20 Thread Robert Kern

On 4/20/10 3:49 PM, Brendan Miller wrote:

On Tue, Apr 20, 2010 at 11:38 AM, Robert Kernrobert.k...@gmail.com  wrote:

On 4/20/10 1:09 PM, Brendan Miller wrote:


Python provides a GNU readline interface... since readline is a GPLv3
library, doesn't that make python subject to the GPL? I'm confused
because I thought python had a more BSD style license.


The PSF License is more BSD-styled, yes. The readline module can also be
built against the API-compatible, BSD-licensed libedit library. Python's
source distribution (even the readline module source) does not have to be
subject to the GPL, though it should be (and is) GPL-compatible.


Also, I presume programs written with the readline interface would
still be subject to GPL... might want to put a warning about that in
the python library docs.


*When* someone builds a binary of the Python readline module against the GNU
readline library, then that binary module is subject to the terms of the
GPL. Any programs that distribute with and use that binary are also subject
to the terms of the GPL (though it can have a non-GPL, GPL-compatible
license like the PSF License). This only applies when they are combined with
the GNU readline library, not before. The program must have a GPL-compatible
license in order to be distributed that way. It can also be distributed
independently of GNU readline under any license.



Hmm... So if I ship python to a customer with proprietary software
that runs on top of it, then I need to be careful to disable
libreadline? Is there a configure flag for this or something?


Just don't ship the readline.so module. That's the only thing that links to 
libreadline.



Since libreadline is the default for Linux systems, and Python's
license advertises itself as not being copyleft, and being embeddable
and shippable... It would be nice if this were made clear. Maybe a
note here about libreadline: http://python.org/psf/license/


http://bugs.python.org


It seems to me that the whole of the python distribution would be GPL
after being built with libreadline, so this would be an easy trap to
fall into if you didn't realize that python used libreadline.


No, the whole Python distribution does not magically become GPLed because one 
optional module that you may or may not load is compiled against a GPLed library.


--
Robert Kern

I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth.
  -- Umberto Eco

--
http://mail.python.org/mailman/listinfo/python-list


Re: gnu readline licensing?

2010-04-20 Thread Irmen de Jong

On 20-4-2010 20:09, Brendan Miller wrote:

Python provides a GNU readline interface... since readline is a GPLv3
library, doesn't that make python subject to the GPL? I'm confused
because I thought python had a more BSD style license.

Also, I presume programs written with the readline interface would
still be subject to GPL... might want to put a warning about that in
the python library docs.


IANAL but I think because Python itself doesn't include the readline library as part of 
the distribution (it is installed on your system by other means), you have nothing to 
worry about. Only when you start to include it as part of your program, then you have to 
worry about the license(s) involved. But I can be wrong here.


-irmen


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