In Python, calling = causes a reference to be made to the matrix, but in C++ it creates a view. This leads to the following code not being translatable to C++:

import numpy as np
a = np.array([1,2,3,4])
b = a
a.shape = (2,2)
print(b.ndim)

of course in C++ there is no way to set the dims member of an existing matrix anyway, but I worry there may be other ways the abstraction leaks.