See if value has been passed from method

I believe in we have the IsMissing variable to determine wether a value has been passed. How would you do the same thing in Xojo, and what is the most efficient way of doing it? Thanks

Do you mean in a situation like the following?

sub something(optional a as integer = 123)

In this situation it is impossible for the method to prove that the caller omitted the value for a from its parameter list.

Alternatively, you might consider using overloading to achieve it:

sub something()

end sub

sub something(a as integer)

end sub