makeDynamicParam.ps1
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<#
.SYNOPSIS Helper for making dynamic parameters with ValidateSets in PowerShell .PARAMETER ParameterName Name of dynamic parameter .PARAMETER MakeList A scriptblock to create the ValidateSet list .PARAMETER Alias Alias for parameter .PARAMETER ParameterSetName Parameter set name .PARAMETER Mandatory If the parameter is mandatory .PARAMETER ValueFromPipeline If the parameter is from the pipeline .PARAMETER Position Position to set .PARAMETER Help Optional help .PARAMETER DebugFile File for outputing debug information, for debugging dyn parameters .EXAMPLE function simpleDynamicParam { [CmdletBinding()] param() DynamicParam { makeDynamicParam "dyn" -MakeList { return 'cow','pig','horse' } } process { Set-StrictMode -Version Latest $dyn = $psboundparameters["dyn"] Write-Verbose "params are $($psboundparameters | out-string)" $dyn } } .EXAMPLE function conditionalDynamicParam { [CmdletBinding()] param( [switch] $Colors ) DynamicParam { makeDynamicParam "dyn" -MakeList { if ( (Test-Path variable:colors) -and $colors ) { 'red','light blue','green' } } } #> function makeDynamicParam { [CmdletBinding()] param( [Parameter(Mandatory,ParameterSetName="ValidateScriptBlock",Position=1)] [Parameter(Mandatory,ParameterSetName="ValidateSet",Position=1)] [string] $ParameterName, [Parameter(Mandatory,ParameterSetName="ValidateScriptBlock")] [scriptblock] $ValidateSetScript, [Parameter(Mandatory,ParameterSetName="ValidateSet")] [string[]] $ValidateSet, [string] $Alias, [string] $ParameterSetName, [switch] $Mandatory, [switch] $ValueFromPipeline, [switch] $ValueFromPipelineByPropertyName, [int] $Position = 0, [string] $Help, [string] $DebugFile, [Parameter(ValueFromPipeline)] [System.Management.Automation.RuntimeDefinedParameterDictionary] $ParamDictionary ) Set-StrictMode -Version Latest function logit($msg) { if ( $DebugFile ) { "$(Get-Date -form 's') $msg" | out-file $DebugFile -Append -Encoding utf8 } } logit "makeDynamicParam for $ParameterName" # create a dictionary to return, if ( !$ParamDictionary ) { $ParamDictionary = new-object -Type System.Management.Automation.RuntimeDefinedParameterDictionary } # create a new [string] dyn parameter with a collection of attributes $attributeCollection = new-object -Type System.Collections.ObjectModel.Collection[System.Attribute] $dynParam = new-object -Type System.Management.Automation.RuntimeDefinedParameter($ParameterName, [String], $attributeCollection) # create a new atrbute for all parameter sets $attributes = new-object System.Management.Automation.ParameterAttribute if ( $ParameterSetName ) { $attributes.ParameterSetName = $ParameterSetName } if ( $Help ) { $attributes.HelpMessage = $Help } $attributes.Mandatory = [bool]$Mandatory $attributes.ValueFromPipeline = [bool]$ValueFromPipeline $attributes.ValueFromPipelineByPropertyName = [bool]$ValueFromPipelineByPropertyName $attributes.Position = $Position logit "Attributes are $(ConvertTo-Json ($attributes | Select-Object * -ExcludeProperty "TypeId") -Depth 1)" if ( $ValidateSetScript ) { try { logit "About to invoke" $ValidateSet = $ValidateSetScript.Invoke() } catch { logit "Exception from ValidateSetScript: $_" } } logit "list is now $($ValidateSet | out-string)" if ( $ValidateSet ) { $paramOptions = New-Object System.Management.Automation.ValidateSetAttribute -ArgumentList $ValidateSet $attributeCollection.Add($paramOptions) } # hook things together $attributeCollection.Add($attributes) $ParamDictionary.Add($ParameterName, $dynParam) return $ParamDictionary } |