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Is there a built-in function to validate a class property that should be a cell array?

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I'm new to classes and learning about how to define properties and validate their values.
I have a class with a property A that is a cell array of doubles (possibly matrices). For example:
A =
1×2 cell array
{[0.7000]} {[0.9000]}
classdef MKFObserver < matlab.mixin.Copyable
properties (SetAccess = immutable)
Ts {mustBeNumeric}
n {mustBeInteger}
A % how to validate this?
P {mustBeNumeric}
Q {mustBeNumeric}
R {mustBeNumeric}
Can I use a built in function like {mustBeNumeric} or do I need to write my own validation function?
Bill Tubbs
Bill Tubbs on 4 Jun 2022
Edited: Bill Tubbs on 4 Jun 2022
Thanks. That will do the first part. But I'll have to upgrade my MATLAB now! (Introduced in R2020b). I admit I have been putting it off for too long...

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Accepted Answer

Edric Ellis
Edric Ellis on 6 Jun 2022
Rather than a validator, you could perhaps just use the class specification? (In my code below I'm using a function with an arguments block, but the syntax is exactly the same as a properties block in a classdef). Note that this will accept anything that can be converted to a cell, if you care about distributed arrays, then you should use the approach suggested by @Sean de Wolski.
myFcn({1,2}); % works
myFcn([1,2]); % fails
Error using solution>myFcn
Invalid argument at position 1. Value must be of type cell or be convertible to cell.
function myFcn(in)
in (1,2) cell
% do stuff
  1 Comment
Bill Tubbs
Bill Tubbs on 6 Jun 2022
Edited: Bill Tubbs on 6 Jun 2022
This worked! I just did this:
classdef MKFObserver < matlab.mixin.Copyable
A cell
B cell
% Test:
>> MKFObserver([0.7 0.9], ...)
Error setting property 'A' of class 'MKFObserver':
Invalid data type. Value must be cell or be convertible to cell
It doesn't check the underlying type of the elements of the cell array but I decided in the end I don't want this level of validation. Thanks.

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More Answers (2)

Matt J
Matt J on 4 Jun 2022
Edited: Matt J on 4 Jun 2022
There is always iscell():
function obj=set.A(obj,A)
assert(iscell(A),'Value assigned to A must be cell array');

Sean de Wolski
Sean de Wolski on 5 Jun 2022
Edited: Sean de Wolski on 5 Jun 2022
I think you'll have to write your own. Must be underlying type is for distributed, gpuArrays and others that masquerade as the underlying type.
Value must have underlying type 'double'.
You could probably get away with this as your validator: cellfun(@(x)mustBeA(x, 'double'),PropertyName)
c = {pi,magic(3)}
d = {pi, "hello"}
cellfun(@(x)mustBeA(x, 'double'),c)
cellfun(@(x)mustBeA(x, 'double'),d)


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