Re: [eigen] StdVector again

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2009/8/28 Markus Moll <markus.moll@xxxxxxxxxxxxxxxx>:
> Hi
> On Thursday 27 August 2009 13:45:40 Markus Moll wrote:
>> the problems reported in the two recent mails on StdVector sounded
>> suspiciously familiar to me.
>> Indeed, both are due to a problem solved quite a while ago, but
>> unfortunately the changes are in the default branch, while the current
>> branch seems to be 2.0, which does not contain them.
> Ah, sorry. If my understanding is correct, the 2.0 branch is the stable
> branch, while default is development (right?)


> Daniel, you essentially ran into two problems. StdVector in 2.0 redefines
> std::vector so that it can be used with aligned Eigen types. What happened is:
> 1. The redefinition of std::vector makes programs compiled with Eigen
> incompatible with libraries that export anything containing std::vector (the
> std::vector type for compiling the library is different from the one used for
> compiling your program).

That's true, this problem exists with Eigen 2.0. Just to make it
clear: it is only with Eigen 2.0, not with the development branch.

> It _might_ work if you carefully include the library
> headers (boost in your case) _before_ including StdVector. Of course, then you
> cannot use any Eigen vectors before that point, either. However, this might be
> arbitrarily complex if not impossible in larger projects.
> 2. The vector interface in the stable branch is not complete and does not
> satisfy the requirements imposed by the standard. This is why your constructor
> call did not succeed.
> To the developers: Would it be possible to include the fixes in the 2.0 branch
> as well?

We can add any missing constructors or assignment operators in the 2.0
branch if that helps. But that would only address issue 2 above.

> Granted, it would change the interface

Indeed, if we wanted to fix issue 1 above, we'd have to break
compatibility. That's not doable at this point: people expect Eigen
2.0.6 to be fully compatible with Eigen 2.0.5.

What I can propose to you is instead to add the development branch's
StdVector as NewStdVector in the 2.0 branch. In this way, people who
want StdVector as in the devel branch would just include NewStdVector
instead of StdVector. So people have choice and compatibility isn't

Daniel, Markus, would you like this?


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