Hi, Thomas!
I don't think it is possible in a way it is done in C, for example.
Depending on your needs you can mark some arguments as optional (but you'll have to define them).
If it's not enough, maybe sending some table of input parameters (e.g., name, type, value) will help you. But I don't think it's a nice solution 
Maybe community gurus can advise a more elegant way of accomplishing your task.