In-Reply-To: <eg3csg$jm9$1@sea.gmane.org> andy@servocomm.freeserve.co.uk (Andy Little) wrote (abridged):

Why not :

at_x(vec)

If we don't mind the syntactic clutter of the function call, we can use vec.x(). double vector::x() const { return data[0]; } double vector::y() const { return data[1]; } This ought to have the runtime efficiency of vec.x while still hiding the internal representation, and supporting indexed access without undefined behaviour. The only argument I can see against it is that some people don't want to have to type the brackets. -- Dave Harris, Nottingham, UK.