Re: [eigen] backporting the vectorized quaternion product to 2.0 ?

[Benoit Jacob <jacob.benoit.1@xxxxxxxxx>]

2009/9/23 Cyrille Berger <cberger@xxxxxxxxxxx>:
> Hi,
>
> Well you could consider to make a 2.1 branch with all the features that are
> backportable (aka that keep API stable) and release that. And declare trunk to
> be future 3.0, and take your time on that.

This would take a lot of effort, I am afraid that it is too big a drag
of resources for us.

> I will also give my 2 cents on API stability, I think it has always been a bit
> overated (there are very successfull project with totally unstable API), there
> are things that make breakeage very bearable:
> 1) the changes need to be well documented
> 2) coinstability of the installation (you do that with the eigen2/3 include),
> 3) keeping to have bug fix release of 2.x even after 3.x is available
> 4) in the case of eigen, it's important that data class of eigen have/get
> stable API/ABI (vectors and matrixes), this would make it possible to have a
> more heterogenous environment (aka use a vector made with an eigen2 library in
> an application used by eigen3) and to be confident in the use of eigen in
> public API of other libraries

2: yes indeed;
1 and 3: yes that's my plan;
4: we have compatibility for the Matrix class but not for all other
classes like decompositions.
Of course, after the 3.0 release we keep everything ABI compatible
exactly for the reason you mention.

Benoit