PowerShell has an extensive parameter handling and validation system that can be used in scripts and functions. The system allows a developer to make parameters mandatory; to define what, if any, positional binding is allowed; to fill parameters from the pipeline; to describe different parameter sets; and to validate the values passed to a parameter. The wealth of options available makes parameter handling a very involved subject.

This chapter explores the following topics:

• The Parameter attribute
• Validating input
• Pipeline input
• Defining parameter sets
• Argument-completers
• Dynamic parameters