These are two small utility functions for parsing function arguments in MATLAB.
See the corresponding post on the Writing Better Code for an introduction.
Example code for a function using parseArgs to provide optional arguments:
function [age] = calculateAgeOfTheUniverse(grandmaAge, nDinosaurs, varargin)
args = parseArgs(varargin, struct('nPlanets', 9, 'electronCharge', 1, ...
'andAnotherArgument', [], 'andAnotherOne', []));
if args.useGeneralRelativity
age = age + 1E6 * args.nPlanets; % not that this makes any sense :)
end
end
Then call the function using, for example:
>> calculateAgeOfTheUniverse(78, 4E7);
>> calculateAgeOfTheUniverse(78, 4E7, 'nPlanets', 8)
>> calculateAgeOfTheUniverse(78, 4E7, 'nPlanets', 8, 'andAnotherOne', 'boo')
You simply pass the varargin cell array into parseArgs, together with a struct with optional arguments. It returns the input struct, amended with the arguments passed into the function.
Note that argument names are case insensitive.
As a nice little extra, parseArgs also provides the option of flag arguments: arguments that don't need a value, and will just toggle the corresponding default value to true:
function myFunc(varargin)
args = parseArgs(varargin, struct('doSomething', false), {'doSomething'})
% pass a cell array of flag arguments into parseArgs as the 3rd parameters
% Then call the function using:
>> myFunc() % it's still optional
>> myFunc('doSomething') % "true" assumed
>> myFunc('doSomething', true) % but you can also give it explicitly
We personally prefer to format our parseArgs code the following way. YMMV :-)
function [age] = calculateAgeOfTheUniverse(grandmaAge, nDinosaurs, varargin)
defArgs = struct(...
'nPlanets', 9 ...
, 'electronCharge', 1 ...
, 'andAnotherArgument', [] ...
, 'andAnotherOne', [] ...
, 'useGeneralRelativity', false ...
);
args = parseArgs(varargin, defArgs, {'useGeneralRelativity'});
Another suggested format would be:
function [age] = calculateAgeOfTheUniverse(grandmaAge, nDinosaurs, varargin)
defArgs = struct();
defArgs.nPlanets = 9;
defArgs.electronCharge = 1;
defArgs.andAnotherArgument = [];
defArgs.andAnotherOne = [];
defArgs.useGeneralRelativity = false;
args = parseArgs(varargin, defArgs, {'useGeneralRelativity'});
If an argument has a cell array as a default value, and you're not using the latter format: be careful. Due to the way the struct function works, you'll have to use double braces:
defArgs = struct(...
'cellArray', {{1, 'two', [3 3 3]}} ...
);
As a bonus, an additional function parseClassAgs has been included in this repo. It's similar to parseArgs, but applies to class properties instead of function arguments. Note that this one is case sensitive.
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