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How to make user-defined type pass as numeric?

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Suppose I have a defined type that behaves like a number. I would like it to pass the test:
validateattributes(x, {'numeric'}, {})
It's not enough, apparently, to overload the function isnumeric.m. What else needs to be done?
Thanks, n

Accepted Answer

Geoff Hayes
Geoff Hayes on 10 Oct 2015
Edited: Geoff Hayes on 10 Oct 2015
Naor - try overloading the isa function instead. For example, let's suppose that the following class is "numeric".
classdef MyNumberClass
properties
x
end
methods
function obj = MyNumberClass(varargin)
if nargin > 0
obj.x = 42;
else
obj.x = 99;
end
end
function [result] = isa(obj,typeStr)
result = false;
if strcmpi(typeStr,'numeric') || strcmpi(typestr,'MyNumberClass')
result = true;
end
end
end
end
Then in the Command Window, try the following
myInstance = MyNumberClass;
Now try to validate it as
validateattributes(myInstance, {'numeric'}, {})
No error is thrown and so the object is considered to be numeric. Note that you would need to overload isnumeric so that that function "passes" too.
  2 Comments
Geoff Hayes
Geoff Hayes on 10 Oct 2015
Naor - I've updated the solution with your suggestion. As for including your class in the error output, I'm not sure how that can be done.

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