PowerShell Functions and Modules

Overview

Functions encapsulate reusable logic, while modules package related functions for distribution and versioning.

Function Design

• Use [CmdletBinding()] for advanced behavior
• Validate inputs with parameter attributes
• Return objects for downstream automation
• Add help comments for discoverability

flowchart TD
    A[Function] --> B[Input Validation]
    B --> C[Business Logic]
    C --> D[Object Output]

Practical Example

function Get-DiskSummary {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory)]
        [string]$ComputerName
    )

    Get-CimInstance Win32_LogicalDisk -ComputerName $ComputerName |
      Select-Object DeviceID, FreeSpace, Size
}

Production Example

Platform teams publish internal modules for onboarding checks, deployment approvals, and compliance audits.

Import-Module Company.PlatformOps
Test-PlatformReadiness -Environment prod

Common Pitfalls

• Large functions with mixed responsibilities
• Script-scoped variables causing hidden side effects
• Missing semantic versioning in module releases

Key Takeaways

• Functions improve reuse and consistency.
• Modules support scaling scripting standards across teams.
• Object-based outputs keep automation composable.