Re: [eigen] Eigen C++11 alias templates

[Gael Guennebaud <gael.guennebaud@xxxxxxxxx>]

Hi,

I agree such generic typedefs are be very useful. They also involve few lines of code. However, with respect to our recent discussion on C++11 features, this is for me a borderline one because when you're using e.g.:

VectorX<float>

there is nothing that make it clear you are using a C++11 feature. Actually similar declarations would be possible in C++03 with a more complex class hierarchy, much more code boilerplate and some other drawbacks... So, in my opinion such an addition should go in a separate C++11 module.

gael

On Thu, Feb 13, 2014 at 12:03 AM, Jim Garrison <jim@xxxxxxxxxxx> wrote:

Hi all,

Another C++11 feature I'd like to see available to users is alias
templates for commonly used types.

Currently, users can create e.g. an arbitrary sized matrix of doubles
using the Eigen::MatrixXd typedef, defined in Eigen/src/Core/Matrix.h.
However, if one wants to do this with a templated type, it is necessary
to write out in full each time:

    Eigen::Matrix<T, Eigen::Dynamic, Eigen::Dynamic> mat;

The attached header defines alias templates similar to MatrixXd, etc.,
which allow for the same functionality with less verbosity.  With this,
the above type definition can be written as:

    Eigen::MatrixX<T> mat;

I've been using this now for several months and it makes my code much
clearer.  Please feel free to adapt it and include it in Eigen.

Regards,
Jim