Get-ADObjectFromPipeline.ps1

function Get-ADObjectFromPipeline {
    <#
        .SYNOPSIS
            Determines the type of an object passed to the pipeline and returns the object as an ADObject.
        .DESCRIPTION
            Determines the type of an object passed to the pipeline and returns the object as an ADObject. Potentially
            useful for normalizing input to other functions.
    #>
    [CmdletBinding()]
    param (
        [Parameter(Mandatory, ValueFromPipeline, ValueFromPipelineByPropertyName)]
        [ValidateNotNullOrEmpty()]
        $Identity
    )

    begin {
        Import-Module ActiveDirectory
    }

    process {
        # Resolve identity type in process block where pipeline input ($Identity) is available.
        if ($Identity -is [Microsoft.ActiveDirectory.Management.ADUser]) {
            # We have an ADUser object
            # Might want to normalize the type to an ADObject IF we can get sidHistory from an ADObject
        }
        if ($Identity -is [Microsoft.ActiveDirectory.Management.ADComputer]) {
            # We have an ADComputer object
            # Might want to normalize the type to an ADObject IF we can get sidHistory from an ADObject
        }
        if ($Identity -is [string]) {
            # Find an AD object and determine its type
            $Identity = Get-ADObject -Filter "Name -eq `"$Identity`""
        }
        $IdentityType = $Identity.ObjectClass
        switch ($IdentityType) {
            'user' {
                # Not Complete
                Get-ADUser -Identity $Identity -Properties PrimaryGroup,SidHistory
            }
            'computer' {
                # Not Complete
                Get-ADComputer -Identity $Identity -Properties PrimaryGroup,SidHistory
            }
            Default {
                Write-Error "Identity type not supported."
            }
        }
    }
}