Re: One unclear point in the Vim license
Bram Moolenaar <Bram@moolenaar.net> writes:
> > The GPL does not require that you keep the source code forever. When
> > I give a copy to my friend, I have finished all my responsibilities.
> > I have no requirement to keep a copy, or know how to get in touch with
> > my friend next year.
>
> The Vim license also doesn't require you keep the source code forever.
If I distribute a modified copy, and lose my copy, and lose track of
the person I gave it to, and you come to me and say "I hereby demand
that you give me your changes", I will be in violation of the
license. The only way I could reliably meet that demand is by keeping
a copy myself. How long would I have to keep it? Since the license
gives no time limit, I would need to keep it forever--for as long as
you could make the demand.
> > It also does not require that I send the changes to the maintainer.
> > That's the sticking point.
>
> The GPL requires you to make the source code available to every user.
No, only to the people you give copies to. If you don't want a
copyleft, then don't make one.
> Neither the GPL nor the Vim license explicitly require you to keep the
> changes around. Only in specific cases you might have to keep a copy
> as a consequence of choices you make.
If you ever distribute a modified copy, the vim license essentially
requires you to keep the changes around, forever.
> With the GPL you also get into
> this situation if you give someone only the executable. Then you need
> to allow the user to get the source code later, thus you need to keep a
> copy.
Right, but its easy to avoid that--just distribute the source together
with the binary. In the case of vim, there's no way to avoid that.
Moreover, in the case of the GPL, the requirement is limited to three
years; the vim license gives no limitation.
> When someone vanishes I can't ask them for the changes, right? Or hit
> them on the head because he didn't follow the rules of the license. So
> this is irrelevant.
No, it's not.
> If you don't want to explain your point then it doesn't make sense to
> continue this discussion. You didn't mention the part of the DFSG that
> the Vim license would not meet.
I don't need to defend whatever past decisions may have been made;
they quite possibly were simply incorrect.
It's up to you to license vim under whatever terms you deem
appropriate. But it's up to Debian to then evaluate whether those
terms meet the DFSG or not.
Sometimes people offer licenses in which any changes must be sent to
some specific place. The problem with those licenses is that it
cannot be satisfied by people who lack the ability to send the changes
off to that place. (And thus it violates DFSG 1-3.)
The vim license is like this, except that it only applies if the vim
maintainer requests that the changes be sent to him. However, that
doesn't fix the problem, because it still might be impossible to send
the changes back.
A good test case for whether a license is free (for issues like this)
is whether a disconnected group of people on a desert island could
distribute the software among themselves. In the vim case, they
cannot. (For example, if the vim maintainer flies over the island and
drops down a message saying "you must hereby send me your changes",
how are the people down below to comply?) The fact that the vim
maintainer can send the request does not say anything about whether
the people receiving it could reply.
Also, free software needs to be usable in seekrit environments.
Sample situations are people living under repressive regimes who want
to keep their use of the software entirely secret.
Thomas
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