PowerShell Generating dynamic parameters and parameter sets to wrap around a Class for easy instantiation such as new-Type -ctorArg1 $val -property $val2

DynamicParam.draft.ps1

#region Get-TypeDynamicParam
function Get-DynamicParamFromTypeName {
	Param(
		[string]
		$TypeName
	)
	function New-ParamAttribute {
		Param(
			[Parameter(Mandatory=$true,ValueFromPipeLine=$false,ValueFromPipelineByPropertyName=$true, position=0)]
			[string]
			$ParameterSetName,
			[Parameter(Mandatory=$true,ValueFromPipeLine=$false,ValueFromPipelineByPropertyName=$true, position=1)]
			[int]
			$paramPosition,
			[Parameter(Mandatory=$false,ValueFromPipeLine=$false,ValueFromPipelineByPropertyName=$true, position=2)]
			[switch]
			$DontShow,
			[bool]
			[Parameter(Mandatory=$false,ValueFromPipeLine=$false,ValueFromPipelineByPropertyName=$true, position=3)]
			$mandatory = $true
		)
		$newAttribute = New-Object System.Management.Automation.ParameterAttribute
		$newAttribute.Mandatory = $mandatory
		if($DontShow) {$newAttribute.DontShow = $false}
		$newAttribute.Position = $paramPosition #This is new attribute, so always 1 (first parameter defining type - non dynamic)
		$newAttribute.ParameterSetName = $ParameterSetName
				
		return $newAttribute
	}

	$paramRuntimeCollection = New-Object System.Management.Automation.RuntimeDefinedParameterDictionary
		
	$type = $TypeName -as [type]
	foreach($constructorDefinition in $type.GetConstructors().Where({($_.GetParameters().ParameterType.name -join '') -notmatch '\*'})) {
		$paramListForParamSet = @()
		$ParamsInCtor = $constructorDefinition.GetParameters()
		$constructorIndex = $ParamsInCtor.Name -join '.'
		foreach ($ParamDefinition in $ParamsInCtor) {
			$paramPosition = 1
			if ($paramRuntimeCollection.keys -notcontains $ParamDefinition.Name) {
				$newRuntimeDefinedParameter = New-Object System.Management.Automation.RuntimeDefinedParameter
				$newRuntimeDefinedParameter.Name = $ParamDefinition.Name
				$newRuntimeDefinedParameter.ParameterType = $ParamDefinition.ParameterType
				$newRuntimeDefinedParameter.Attributes.Add((New-ParamAttribute -ParameterSetName "ctor_$constructorIndex" -paramPosition $paramPosition))
				if ($ParamDefinition.HasDefaultValue) {
					$newRuntimeDefinedParameter.Value = $ParamDefinition.DefaultValue
				}
				$paramRuntimeCollection.Add($newRuntimeDefinedParameter.Name,$newRuntimeDefinedParameter)
			}
			else {
				"$($ParamDefinition.Name) already present in Attribute collection" |  Write-Debug
				"Adding Attribute definition for ParameterSet $($constructorIndex) for Parameter $($ParamDefinition.Name)" |  Write-Debug
				$paramRuntimeCollection[$ParamDefinition.Name].Attributes.Add((New-ParamAttribute -ParameterSetName "ctor_$constructorIndex" -paramPosition $paramPosition))
			}
			$paramListForParamSet+= $ParamDefinition.Name
		}
		$paramPosition++
	}
		
	$writeableProperties = $type.GetProperties().Where({$_.CanWrite -and $_.Name -notin $paramRuntimeCollection.keys})
	foreach($propertyArgument in $writeableProperties){
		$newRuntimeDefinedParameter = New-Object -TypeName System.Management.Automation.RuntimeDefinedParameter
		$newRuntimeDefinedParameter.Name = $propertyArgument.Name
		$newRuntimeDefinedParameter.ParameterType = $propertyArgument.PropertyType
		$newRuntimeDefinedParameter.Attributes.Add((New-ParamAttribute -ParameterSetName '__AllParameterSets' -paramPosition -2147483648 -mandatory $false))
		$paramRuntimeCollection.Add($newRuntimeDefinedParameter.Name,$newRuntimeDefinedParameter)
	}
		
	return $paramRuntimeCollection
}
#endregion

#region New-ObjectInstanceFromTypeNameAndBoundParams
function New-ObjectInstanceFromTypeNameAndBoundParams {
	Param (
		[Parameter(Mandatory=$true,Position=0,ValueFromPipeline=$false)]
		#[validateScript({if($_ -as [type]){$true}else{$false}})]
		[string]
		$TypeName,

		[Parameter(Mandatory=$true,Position=0,ValueFromPipeline=$false)]
		[string[]]
		$StaticArgumentName,

		[Parameter(Mandatory=$true,Position=0,ValueFromPipeline=$false)]
		[string]
		$ParameterSetName,
		
		[Parameter(Mandatory=$true,Position=0,ValueFromPipeline=$false)]
		[validateNotNullOrEmpty()]
		[hashtable]
		$BoundParameters
	)
	Process {
	
		$ConstructorParameterNames = @()
		if($ParameterSetName -match '^ctor_') {
			$ConstructorParameterNames = $ParameterSetName -replace '^ctor_' -split '\.'
		
			$parameters = @()
			$ConstructorParameterNames.ForEach({$parameters+=$BoundParameters[$_];$BoundParameters.Remove($_)})
			$instanceOfObject = New-Object -TypeName $typeName -ArgumentList $parameters
		} else {
			$instanceOfObject = New-Object -TypeName $typeName 
		}
		$setProperties = $BoundParameters.Keys.Where({$_ -notin $StaticArgumentName -and $_ -notin [System.Management.Automation.PSCmdlet]::CommonParameters -and $_ -notin [System.Management.Automation.PSCmdlet]::OptionalCommonParameters})
		foreach ($ParamPropKey in $setProperties) {
			$instanceOfObject.($ParamPropKey) = $BoundParameters.($ParamPropKey)
		}
		$instanceOfObject
	}
}
#endregion


function New-DateTime {
	[cmdletBinding()]
	Param (
		[Parameter(Mandatory=$false,ValueFromPipeLine=$false,ValueFromPipelineByPropertyName=$true, position=0)]
		[ValidateSet('datetime','System.datetime')]
		[type]
		$typename = 'datetime'
	)
	DynamicParam {
		if ($PSBoundParameters.Keys -notcontains 'typename')
		{
			$typename = 'datetime'
		}
		$type = ($typename -as [Type])
		Get-DynamicParamFromTypeName -TypeName $type.ToString()
	}
	
	Process {
		New-ObjectInstanceFromTypeNameAndBoundParams -TypeName $type.ToString() -StaticArgumentName 'TypeName' -ParameterSetName $PSCmdlet.ParameterSetName -BoundParameters $PSBoundParameters
	}
}

#when the above is loaded, try to type New-Datetime - and see the magic happening!