Passing Arguments as Ref type deduction - eigen3

Question

i my settings looks like:
class Base
{
public:
virtual void eval(const Ref< const Matrix<float,Dynamic,1>> in, Ref<Matrix<float,Dynamic,1>> out) = 0;
virtual void eval( const Ref< const Matrix<float,Dynamic,Dynamic,RowMajor>> inp, Ref<Matrix<float,Dynamic,Dynamic,RowMajor>> out) = 0;
};
class Test : Base
{
public:
void eval(const Ref< const Matrix<float,Dynamic,1>> in, Ref<Matrix<float,Dynamic,1>> out) override
{
out = in;
};
void eval( const Ref< const Matrix<float,Dynamic,Dynamic,RowMajor>> in, Ref<Matrix<float,Dynamic,Dynamic,RowMajor>> out)override
{
for(std::size_t i=0;i<in.rows();i++)
eval( in.row(i).transpose(), out.row(i).transpose() );
};
};
The compiler Error looks like:
In file included from main.cc:2:0:
../tmp.hpp: In member function ‘virtual void eval(Eigen::Ref<const Eigen::Matrix<float, -1, -1, 1> >, Eigen::Ref<Eigen::Matrix<float, -1, -1, 1> >)’:
../tmp.hpp:36:62: error: call of overloaded ‘eval(Eigen::DenseBase<Eigen::Block<const Eigen::Ref<const Eigen::Matrix<float, -1, -1, 1> >, 1, -1, true> >::ConstTransposeReturnType, Eigen::Transpose<Eigen::Block<Eigen::Ref<Eigen::Matrix<float, -1, -1, 1> >, 1, -1, true> >)’ is ambiguous
eval( in.row(i).transpose(), out.row(i).transpose() );
^
../tmp.hpp:25:7: note: candidate: virtual void eval(Eigen::Ref<const Eigen::Matrix<float, -1, 1> >, Eigen::Ref<Eigen::Matrix<float, -1, 1> >)
void eval(const Ref<const Matrix<float, Dynamic, 1>> input,
^
../tmp.hpp:32:7: note: candidate: virtual void eval(Eigen::Ref<const Eigen::Matrix<float, -1, -1, 1> >, Eigen::Ref<Eigen::Matrix<float, -1, -1, 1> >)
void eval(const Ref<const Matrix<float, Dynamic, Dynamic, RowMajor>> input,
^
make: *** [main.o] Error 1
I found this. The types doesn't match, but for me it is not clear how to solve this elegant ( without template's because of the base class )

Answer 1

Indeed, when calling eval with vectors, both overloads can be matched. One solution would be to rename the two overloads to distinct names (e.g., evalVec and evalMat), and add a thin template method dispatching to the correct one:
template<typename A, typename B>
void eval(const MatrixBase<A> &a, MatrixBase<B> &b,
typename enable_if<A::IsVectorAtCompile,void*>::type = 0) {
this->evalVec(a.derived(),b.derived());
}
template<typename A, typename B>
void eval(const MatrixBase<A> &a, MatrixBase<B> &b,
typename enable_if<!A::IsVectorAtCompile,void*>::type = 0) {
this->evalMat(a.derived(),b.derived());
}