Re: Interpreted octave code and GPL

[Richard Crozier]

On 20/08/2012 12:32, Francesco Potortì wrote:
> > On 19/08/2012 17:15, Carnë Draug wrote:
> > Ok, but lets put it another way, lets say I write an function in
> > interpreted code and release it under the GPL. Can this then be taken by
> > others and used in a non-free program?
> You write a GPL function.  I have a non-free program (or more generally,
> a GPL-incompatible program) that needs your function.  My program can
> happily and legitimally use your function.  However, if I distribute my
> program, I must do it under the terms of the GPL.
>
> This is a generic answer to a generic question.  If you want more detail,
> you must provide more.
>
> > If not, then why can I call the Octave core m-files in a non-free
> > program, which is what is implied by the wiki? Surely they're exactly
> > the same, but just have a different origin.
> I'd say Octave is an environment, and the core m-files are part of the
> environment.  You install the environment in your box.  I give you the
> program.  If, on the other hand, I distribute my program together with
> the environment, then I must do so under the GPL.  I think this is the
> rationale behind
> http://wiki.octave.org/FAQ#If_I_write_code_using_Octave_do_I_have_to_release_it_under_the_GPL.3F
>
> Am I right?

Ok, I think I see what you're getting at. I effectively can use the name 
or function calling syntax of any function in a non-free program, but I 
could not distribute the actual code implementing that function with my 
program if it is not GPL?

But on the FSF FAQ it states that

"A system incorporating a GPL-covered program is an extended version of 
that program. The GPL says that any extended version of the program must 
be released under the GPL if it is released at all."

it goes on to say

"However, in many cases you can distribute the GPL-covered software 
alongside your proprietary system. To do this validly, you must make 
sure that the free and non-free programs communicate at arms length, 
that they are not combined in a way that would make them effectively a 
single program."

I don't really see how having a call to a GPL m-file function in my 
program could be considered "at arm's length".

Is it because we take Octave and it's core m-files to be a "Standard 
Interface" as defined in the GPL?



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