On Monday, January 18, 2016 at 11:54:49 AM UTC-5, Anonymous wrote:
>
> As you can see, I have to define a whole other type tree just so my metric
> function can distinguish between sphere manifolds depending on what metric
> structure I want it to have. It would be both simpler and make more sense
> conceptually to attach the metric to the manifold itself when I instantiate
> it.
>
Here's another alternative:
@enum Metric RIEMANNIAN LORENTZIAN # ...
immutable Sphere
dim::Int
metric::Metric
end
function metric(s::Sphere)
if s.metric == RIEMANNIAN
# …
elseif s.metric == LORENTZIAN #…
end
end
The key point is that you don't always need to attach a function — you can
attach data that describes the object's properties, and then use that in
your external functions.
(This is crossposted
at
http://stackoverflow.com/questions/34841635/immutable-type-with-function-fields-in-julia)
