Thread Subject: preallocation for object array

Typically if you're going to loop and grow a vector in matlab you'd like to preallocate first. for example:

vec = zeros(N,1);
for i = 1:N
   vec(i) = someNumber
end

But what if I have some class

classdef point

   properties
     x
     y
   end

...

where x and y are a single double.

How would I preallocate for a vector of point objects?