Of course you can check the name of the function before calling using STRCMP.
In such cases it is often more preactical to define the input arguments as cell:
Inputs = {arg1,arg2,arg3,arg4,arg5};
feval(function_name, Inputs{:})
Or the equivalent method for 8 inputs.
Anyhow, I do not have the impression, that I got your problem completely.