Hello,

I would like to declare an array based on Eigen::Quaternionf. The more I pull on what I need to forward declare from Eigen in order to do so, the more I have to forward declare and it is becoming heavy to handle. I currently have:

Code: Select all

#pragma once

#include <vector>

namespace Eigen // I use this namespace because I want to add things to Eigen.
{
template<typename _Scalar, int Options = AutoAlign> class Quaternion; // Forward declaration of Quaternion.

typedef Quaternion<float> Quaternionf; // Forward declaration of typedef Quaternionf.

typedef std::vector<Quaternionf> QuaternionfArray;
} // namespace Eigen.


AutoAlign is yet to be forward declared in this code, but it is already becoming unmanageable as is...

Is there a smart way to handle this?

Thanks

Antoine.

PS: I am not even sure the default argument for template parameter 'Options' is 'AutoAlign', does anyone confirm?

Because Eigen is so heavily templated, it will be difficult to forward declare it. Just include Eigen/Geometry in your header. A very long time ago, we tried to define a ForwardDeclare header for Eigen, but the gain in term of compilation speed was negligible, so we gave up. Precompiled-header are much more effective.

Well, for Quaternion, the following should do the job though:

template<typename _Scalar, int Options = 0> class Quaternion;

Whenever possible, we make sure that optional parameters default to 0.

Very helpful!

Hum, and for the multiple definitions, what do you advise me? There is not much else than ignoring the warnings I guess?

Thanks.

yep, no trick for that one.

Done, thanks for your answer!