Advanced Functions

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Advanced functions behave the in the same way as cmdlets. The PowerShell ISE includes two skeletons of advanced functions. Access these via the menu, edit, code snippets, or by Ctrl+J. (As of PS 3.0, later versions may differ)

Key things that advanced functions include are,

built-in, customized help for the function, accessible via Get-Help
can use [CmdletBinding()] which makes the function act like a cmdlet
extensive parameter options

Simple version:

<#
.Synopsis
   Short description
.DESCRIPTION
   Long description
.EXAMPLE
   Example of how to use this cmdlet
.EXAMPLE
   Another example of how to use this cmdlet
#>
function Verb-Noun
{
    [CmdletBinding()]
    [OutputType([int])]
    Param
    (
        # Param1 help description
        [Parameter(Mandatory=$true,
                   ValueFromPipelineByPropertyName=$true,
                   Position=0)]
        $Param1,

        # Param2 help description
        [int]
        $Param2
    )

    Begin
    {
    }
    Process
    {
    }
    End
    {
    }
}

Complete version:

<#
.Synopsis
   Short description
.DESCRIPTION
   Long description
.EXAMPLE
   Example of how to use this cmdlet
.EXAMPLE
   Another example of how to use this cmdlet
.INPUTS
   Inputs to this cmdlet (if any)
.OUTPUTS
   Output from this cmdlet (if any)
.NOTES
   General notes
.COMPONENT
   The component this cmdlet belongs to
.ROLE
   The role this cmdlet belongs to
.FUNCTIONALITY
   The functionality that best describes this cmdlet
#>
function Verb-Noun
{
    [CmdletBinding(DefaultParameterSetName='Parameter Set 1', 
                  SupportsShouldProcess=$true, 
                  PositionalBinding=$false,
                  HelpUri = 'http://www.microsoft.com/',
                  ConfirmImpact='Medium')]
    [OutputType([String])]
    Param
    (
        # Param1 help description
        [Parameter(Mandatory=$true, 
                   ValueFromPipeline=$true,
                   ValueFromPipelineByPropertyName=$true, 
                   ValueFromRemainingArguments=$false, 
                   Position=0,
                   ParameterSetName='Parameter Set 1')]
        [ValidateNotNull()]
        [ValidateNotNullOrEmpty()]
        [ValidateCount(0,5)]
        [ValidateSet("sun", "moon", "earth")]
        [Alias("p1")] 
        $Param1,

        # Param2 help description
        [Parameter(ParameterSetName='Parameter Set 1')]
        [AllowNull()]
        [AllowEmptyCollection()]
        [AllowEmptyString()]
        [ValidateScript({$true})]
        [ValidateRange(0,5)]
        [int]
        $Param2,

        # Param3 help description
        [Parameter(ParameterSetName='Another Parameter Set')]
        [ValidatePattern("[a-z]*")]
        [ValidateLength(0,15)]
        [String]
        $Param3
    )

    Begin
    {
    }
    Process
    {
        if ($pscmdlet.ShouldProcess("Target", "Operation"))
        {
        }
    }
    End
    {
    }
}

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