Why VBScript built-in function do have optional parameters or method oveloads, and I can't?

Question

I do know VBScript does not have method overloads or optional parameters, but some built in methods like InStr (and may others) can be called in different ways (e.g. InStr([start,] string1, string2 [, compare])).

Are they optional parameters or method overloads?

How are they possible?

What is the reason because the language can do this, but the developer not?

Answer 1

The InStr function has been a part of just about every incarnation of BASIC I can think of, including VBScript. I believe, it would have caused more trouble to remove it than to leave it there. Apart from this legacy, VBScript is aim at scripters, i.e. people who need to rapidly/simply perform a task. VBScript presents itself as a simply means to do so. I don't believe many would notice the absence of optional / default parameters.

One cool thing about VBScript is its integration to COM through CreateObject(). This means that any shortfall of VBScript can be overcome via creating code in a different language.

This, I believe, turns VBScript into a powerful tool for both VBScript scripters and developers. Scripters now have a limitless supply of objects that they can leverage from within their scripts, and developers now have a great unit testing platform for their COM objects.