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How to set mutually exclusive arguments in matlab?

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cui
cui on 16 Nov 2020
Commented: cui on 17 Nov 2020
How to use the new "arguments" parameter qualifier to control mutually exclusive two(or more) parameters as function inputs?
for example:
function out = twoStats(x,y)
arguments
% If you have input x, you cannot input y
% If you have input y, you cannot input x
end
end
similar question:

  1 Comment

Jon
Jon on 16 Nov 2020
I have been looking through the documentation. It appears that the input validation only operates on a single argument at a time. I don't see any mechnisim for making the validation of one input dependent upon another, e.g. must be empty if b is not empty. Obviously you could check this yourself, but I understand that you want to use the new argument feature to do this

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Accepted Answer

Bruno Luong
Bruno Luong on 16 Nov 2020
function out = twoStats(x,y)
arguments
x = [];
y {MustBeExclusive(x,y)} = [];
end
% out = ...
end
function MustBeExclusive(varargin)
if sum(cellfun('isempty',varargin)) ~= 1
eid = 'XY:NotExclusive';
msg = 'X and Y must be exclusive.';
throwAsCaller(MException(eid,msg))
end
end

  3 Comments

cui
cui on 17 Nov 2020
By the way, how can I input the parameter y instead of x? For example, I only input y=3, but I cannot call this function. Is the input x or y?
function out = twoStats(x,y)
arguments
x = [];
y {MustBeExclusive(x,y)} = [];
end
out = y; % assume
end
function MustBeExclusive(varargin)
if sum(cellfun('isempty',varargin)) ~= 1
eid = 'XY:NotExclusive';
msg = 'X and Y must be exclusive.';
throwAsCaller(MException(eid,msg))
end
end
out = twoStats(y=3) ?
--------------------
similar question:
Steven Lord
Steven Lord on 17 Nov 2020
>> twoStats([], 5) % x is the "placeholder" empty []
ans =
5
>> twoStats(1, []) % y is empty
ans =
[]
>> twoStats(1) % specify only x, let y take on its default value
ans =
[]
>> twoStats(1, 2) % neither is empty, this is not valid
Error using twoStats
Invalid argument at position 2. X and Y must be exclusive.
I would consider what the condition in MustBeExclusive should be carefully. If specifying both x and y as empties is allowed you should use == 0 instead of ~= 1. Should the following work? Currently it does not.
>> twoStats([], [])
Error using twoStats
Invalid argument at position 2. X and Y must be exclusive.

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