New-DynamicParameter.ps1

Function New-DynamicParameter {

    [cmdletbinding()]
    param(
        [Parameter(Mandatory)]
        [ValidateNotNullOrEmpty()]
        [string]  $Name,

        [string[]] $ValidateSet,
    
        [System.Type] $Type = [string],

        [string[]] $Alias,
    
        [switch] $Mandatory = $false,
    
        [string] $ParameterSetName = "__AllParameterSets",

        [switch] $ValueFromPipeline = $false,
    
        [switch] $ValueFromPipelineByPropertyName = $false,
    
        [string] $HelpMessage,

        [int] $Position = $null,

        [ValidateScript({
            if (-not ($_ -is [System.Management.Automation.RuntimeDefinedParameterDictionary] -or -not $_)) {
                Throw "DPDictionary must be a System.Management.Automation.RuntimeDefinedParameterDictionary object, or not exist"
            }
            $true
        })]
        $DPDictionary = $false
    )

    #Create attribute object, add attributes, add to collection   
    $ParamAttr = New-Object System.Management.Automation.ParameterAttribute

    switch ($PSBoundParameters.Keys) {
        'Mandatory' {$ParamAttr.Mandatory = $true}
        'ValueFromPipeline' {$ParamAttr.ValueFromPipeline = $true}
        'ValueFromPipelineByPropertyName' {$ParamAttr.ValueFromPipelineByPropertyName = $true}
        'ParameterSetName' {$ParamAttr.ParameterSetName = $ParameterSetName}
        'HelpMessage' {$ParamAttr.HelpMessage = $HelpMessage}
        'Position' {$ParamAttr.Position = $Position}
    }

    $AttributeCollection = New-Object Collections.ObjectModel.Collection[System.Attribute]
    $AttributeCollection.Add($ParamAttr)
    
    #parameter validation set if specified
    if ($PSBoundParameters.ContainsKey('ValidateSet')) {
        $ParamOptions = New-Object System.Management.Automation.ValidateSetAttribute -ArgumentList $ValidateSet
        $AttributeCollection.Add($ParamOptions)
    }

    #Aliases if specified
    if ($PSBoundParameters.ContainsKey('Alias')) {
        $ParamAlias = New-Object System.Management.Automation.AliasAttribute -ArgumentList $Alias
        $AttributeCollection.Add($ParamAlias)
    }

    #Create the dynamic parameter
    $Parameter = New-Object -TypeName System.Management.Automation.RuntimeDefinedParameter -ArgumentList @($Name, $Type, $AttributeCollection)
    
    #Add the dynamic parameter to an existing dynamic parameter dictionary, or create the dictionary and add it
    if ($PSBoundParameters.ContainsKey('DPDictionary')) {
        $DPDictionary.Add($Name, $Parameter)
    }
    else {
        $Dictionary = New-Object System.Management.Automation.RuntimeDefinedParameterDictionary
        $Dictionary.Add($Name, $Parameter)
        $Dictionary
    }
}