[Xapian-discuss] Parallel installation of Python bindings

[Olly Betts]

On Tue, May 29, 2007 at 12:23:43PM +0100, Richard Boulton wrote:
> Thomas Waldmann asked me a question on IRC, about how to cope with 
> upgrading his application (MoinMoin) to use the latest version of Xapian 
> if available, but still work with the older releases (so that, for 
> example, users can just use the version of Xapian available from their 
> linux distribution), and, in particular, if other applications require a 
> older Xapian to be installed, how to avoid conflicts.

I don't think this should be necessary - we've tried where possible to
ensure that code that worked with 0.9.x just works with 1.0.0.  If it
used deprecated features which have been removed, it will need updating
but we only removed features which have been deprecated since 0.9.0 or
earlier, so it's easy to update code to work with both 0.9.x and 1.0.0.
That was the main aim of the deprecation policy in my mind.

There are a few exceptions though, such as the return type of
MatchDecider::operator(), but we've typically done this where there's
an easy workaround (in this case, it only affects C++ and C#, and in
both cases the preprocessor can be used to conditionally compile code
with the correct return type).

Is there a particular change that is problematic?  It may be too late to
fix now, but we should certainly try to learn from any such mistakes.
And perhaps we can add a compatibility shim for 1.0.1.

> I thought a bit about this over the weekend, but I can't see any easy 
> way to allow multiple versions of the Xapian python bindings to be 
> installed at once.

Well, you can just follow the "Installing without root access" section
of xapian-bindings' "INSTALL" document.  It's not especially elegant
but it works (it's essentially how we run the "smoketest" for each of
the languages).

> This seems like overkill for the problem, and I can't think of a simpler 
> solution, so I suggest we don't attempt to allow parallel (system-wide) 
> installation of Xapian.

For the bindings I assume you mean?  The library versioning and
libtool's rpath handling mean this should just work for C++.

I think it would be a mistake to add a lot of magic here.  The
"Installing without root access" tips do provide a way for users to make
this work if they really need it; if there are small tweaks to make
those work better, we should probably consider making them.

> Incidentally, Olly is working on debian packages for 1.0.0 (I'm not sure 
> if he's quite finished, but he's certainly made progress), so they'll be 
> available soon.

I'm making progress, but it's taking a lot of iterations because a lot
has changed.  And there's quite a lot of binary packages to build too
which takes time.  Hopefully I should be done this week though.

Cheers,
    Olly