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Optional arguments

Robert Stoner

4 years ago

So I have a function that has multiple optional arguments all Variant. This way I can just do a isMissing(someValue) doSomething. This works when I call it from the code like myFunction(someValue) the isMissing works. Now if I use the same function with a form like myFunction(txtBox1,txtBox2). The first time I run the code it runs fine but then I need to reset txtBox1 and txtBox2. I can set the text boxes to NULL or "" but not Missing. That means isMissing will not work. Right now I am using a Work around I really do not like. By passing the value to a function and turning off error handling then checking if isMissing, isEmpty, or isNull if any return true the function returns true and I resume error handling. I can't see the forest for the trees there has to be a cleaner way to do this I'm sure.

Kevin Yip @Reply

4 years ago

Use an empty string as the default value for your potentially missing argument, so it will never be missing and you never have to use IsMissing(), which is a bit of a pain to use as you've found out.  In all my years I've never used IsMissing(), and I always put default values into optional arguments:

     Function MyFunction(ByVal arg1 As Variant, Optional ByVal arg2 As Variant = "")

To call the function not knowing if arg2 is missing or not (such as when arg2 is from a potentially empty textbox), concatenate the argument with an empty string:

     MyFunction(txtBox1, txtBox2 & "")

That way, the optional argument is always an empty string whether the function is called with an empty textbox or a missing argument.

	Robert Stoner OP @Reply 4 years ago
Kevin thank you for you help.

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