>My initial thought was I should get an error on the call to squareit(), since I am passing a character type when it expects a double. But the error doesn't happen until I perform the calculation. This isn't right! If the caller screws up the function call, I want the error to originate there, not buried in the well-debugged function!
>
>I haven't noticed this before because I assummmed FoxPro was enforcing my explicit type. Am I doing something wrong, or is this just one of FoxPro's quirks?
>
>Using VFP 9, no service pack...
>

In my view, this is what ASSERT is for. You can give the developer a meaningful message. Of course, you still need error-checking at runtime.

Tamar