Arguments function: Name-value arguments in default values

조회 수: 23 (최근 30일)
Austin Pavlas
Austin Pavlas . 2021년 8월 11일
답변: Shivam Malviya . 2023년 3월 7일
I am currently using Matlabs argument validation functionality (arguments) to validation an input struct (via conversion to name-value pair). I was wondering if there is any way to set the default value for name-argument pair as the value from a different name-value pair as below. Ideally this would set the default value of <>.B to be equal to <>.A if the value is not provided.
function my_func(nameValueInputStruct)
nameValueInputStruct.A double = 1
nameValueInputStruct.B double = nameValueInputStruct.A
Matlab throws the error when I try to do this, but was hoping that there is an available work-around. It is important that the input is a name-value pair struct. Thank you.
Use of name-value arguments in default values is not supported.

답변 (2개)

Markus Leuthold
Markus Leuthold 2023년 2월 13일
Same with this code, which I expect to work, but it fails with the same error message
opts.A = mustBeMember(opts.A, ["x" "y"])

Shivam Malviya
Shivam Malviya 2023년 3월 7일
Hi Austin,
I see that you are interested in utilizing the "A" name-value pair argument to assign a default value for the "B" name-value pair argument inside the function argument validation block. However, I regret to inform you that this feature is currently unsupported.
To work around this issue, please note that if a value is not provided for a specific name-value pair argument, it will not appear as a field in the name-value pair argument variable. With this in mind, I have created a function which is attached below for your reference and to help you understand this concept better.
function my_func(nameValueInputStruct)
% Argument validation
nameValueInputStruct.A double = 1
nameValueInputStruct.B double
% Call a helper function to parse the input struct
function parseNameValueInputStruct(nameValueInputStruct)
%parseNameValueInputStruct Parse the nameValueInputStruct and modify it
% accordingly
% If value for argument "B" is not provided
if ~isfield(nameValueInputStruct, "B")
% Set the value of "B" equal to the value of "A"
nameValueInputStruct.B = nameValueInputStruct.A;
Please refer to the following links for a better understanding;
Best regards,
Shivam Malviya


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