Powershell provides a lot of built-in support for common parameter scenarios, including mandatory parameters, optional parameters, "switch" (aka flag) parameters, and "parameter sets."
By default, all parameters are optional. The most basic approach is to simply check each one for
$null, then implement whatever logic you want from there. This is basically what you have already shown in your sample code.
If you want to learn about all of the special support that Powershell can give you, check out these links:
~ Answered on 2012-12-03 17:07:11