Argument validation for class methods (2024)

y=

z=

ans = 2x1 cell array

{'matlab.graphics.axis.Axes'} {'matlab.ui.control.UIAxes' }

ans = 'matlab.graphics.axis.Axes'

Thanks for your reply and the thorough response. But to play Devil's Advocate, you've partially sidestepped the original question. All of the examples (plus, plot, etc.) do not use arguments declarations for validation. If the method in question is written to support varargin inputs, or like plus are designed with internal calls design to sort out how to manage the input arguments, you're probably not using an arguments declaration anyhow.

I'll also grant that the overhead from doing the validation will be minimal in most applications. It's probably safer to include the validation if you expect users to invoke the method with

That way you'll get an error thrown during validation rather than a problem further down the line.

As an aside, I really like arguments as I find it much cleaner and succinct than working with inputParser in many situations. It would be useful to have an additional builtin validator, like mustBeEmptyOrA (e.g., allows an empty default, but if it isn't empty is has to satisfy mustBeA). This comes up often enough that it creates a dependency issue when distributing code.

I used the plus function / method in my example, but your add_to_obj(obj, B) method looks like it is adding together obj and B, doesn't it? So it could be called plus, couldn't it?

Please contact Technical Support directly using this link to submit an enhancement request for mustBeEmptyOrA. When you do, please describe your use case (especially how the lack of it proves to be a problem when you distribute your code.) The developers benefit greatly when designing new features if they have real-world usage stories to help them consider design trade-offs.

My example was really just intended as a minimal demonstration. The real applications were quite different. But thanks nontheless. I'll put in a enhancement request, as you suggest.