What is the best way to check the inputs of a function?

What is the best way to check the inputs of a function in Matlab?

So far I found two 'nice options':

1. Function argument validation
2. validateattributes

What do you think it is the best way? (Also, I have already started using validateattributes and I was wondering if I should change).

Thank you!

[Stephen23]

"What do you think it is the best way?"

"best" is an opinion.... but what are the requirements? Backward compatibility? Efficiency? Code readability? Ease of debugging? Versatility? Compactness? Or https://en.wikipedia.org/wiki/Keeping_up_with_the_Joneses ?

[Lorenzo]

Thanks for answering.

The point is this. Since i do not know much, I wanted the opinion of the community, e.g. what do people (in average) do to solve the problem? I think the question is useful even if it is not specific, I just wanted some general guidance .

However, if I have to be more specific, I would say i do not care about backward compatibility, but i do generally care about the other points (I guess a reduction from 6 options to 5 is still not much : ), but again I just wanted some guidance).

[Stephen23]

"I would say i do not care about backward compatibility, but i do generally care about the other points"

Then probably Function argument validation would be the right choice: neat, simple, easy to use...

[Lorenzo]

Thank you for your answer!

Answer 1

[Adam Danz]

I'm sure there are varying opinions on this. Here are some bits that might help with your decision.

• function argument validation was introduced in R2019b. Will the users of your function all use a release on or after 19b?
• you may find that error messages created by functional argument validation are more intuitive or simpler to understand
• is readability and organization important to you? The functional argument validation is neatly tucked away at the top of the code whereas validateattributes could be sprinkled throughout.
• does functional argument validation or validateattributes have the validation options you need?

As a MATLAB user in grad school, when the new function argument validation feature was released, it took me a while to convert from using validateattributes, primarily because most of the analysis software I wrote needed to function on machines that did not have MATLAB R2019b or later but also because I already was comfortable with validateattributes/validatestring/etc. When I switched over to using the new argument validation feature, I soon felt like it delivered a more consistent experience for the developer and for the user.

[Walter Roberson]

@Adam Danz

Would you happen to have examined the relative performance of the different styles?

Although input validation is often only a small part of the execution time of a function, there are some cases where historically the argument validation has been relatively expensive compared to the execution of the code.

[Adam Danz]

I haven't compared performance between validation techniques but I've wondered about this, too.

[Lorenzo]

Thank you for your answer, this is is pretty useful. I will stick with validateattributes since i have already 10/15 functions with it. I might switch when i have some time.