Thread Subject: Object oriented programming question

Hi,

I have the following situation:

I have an abstract handle class A

classdef A < handle
    methods(Abstract)
        ...
    end
end

and two subclasses B and C

classdef B < A
    ...
end

classdef C < A
    ...
end

I would like to read from a file, create an object of type
B or C depending on what is read, and store it in an array:

ha = [];
while not end of file
    read line
    if cond
       h = B(...);
    else
       h = C(...);
    end
    ha = [ha h];
end while

I have the following questions:
1. Is this possible, or does ha need to be a cell array?
2. IS there a way of not growing the array and preallocate?

Thank you.

Siva