Get-ChildItem.Polyfill.ps1

if ((Get-Command Get-ChildItem).parameters.Keys -notcontains "File") {
    function global:Get-ChildItem {
		[CmdletBinding(DefaultParameterSetName = 'Items', SupportsTransactions = $true)]
        param(
            [Parameter(ParameterSetName = 'Items', Position = 0, ValueFromPipeline = $true, ValueFromPipelineByPropertyName = $true)]
            [string[]]
            ${Path},

            [Parameter(ParameterSetName = 'LiteralItems', Mandatory = $true, ValueFromPipelineByPropertyName = $true)]
            [Alias('PSPath')]
            [string[]]
            ${LiteralPath},
			
            [Parameter(Position = 1)]
            [string]
            ${Filter},

            [string[]]
            ${Include},

            [string[]]
            ${Exclude},

            [Alias('s')]
            [switch]
            ${Recurse},

            [uint32]
            ${Depth},

            [switch]
            ${Force},
			
	    [switch]
            ${File},

	    [switch]
            ${Directory},
			
            [switch]
            ${Name})

        dynamicparam {            
            if ($PSBoundParameters.Path) { $GciPath = $PSBoundParameters.Path }
            elseif ($PSBoundParameters.LiteralPath) { $GciPath = $PSBoundParameters.LiteralPath }
            else { $GciPath = "." }
            $DynParamDictionary = New-Object System.Management.Automation.RuntimeDefinedParameterDictionary            
            $Parameters = Get-Command -CommandType Cmdlet -Name Microsoft.PowerShell.Management\Get-ChildItem -ArgumentList $GciPath |
            	Select-Object -ExpandProperty Parameters
            foreach ($Parameter in ($Parameters.GetEnumerator() | Where-Object { $_.Value.IsDynamic })) {
                $DynamicParameter = New-Object System.Management.Automation.RuntimeDefinedParameter (
                    $Parameter.Key,
                    $Parameter.Value.ParameterType,
                    $Parameter.Value.Attributes
                )
                $DynParamDictionary.Add($Parameter.Key, $DynamicParameter)
            }            
            $DynParamDictionary			
        }

        begin {
            try {				
                $outBuffer = $null				
                if ($PSBoundParameters.TryGetValue('OutBuffer', [ref]$outBuffer)) {
                    $PSBoundParameters['OutBuffer'] = 1
                }				
                $wrappedCmd = $ExecutionContext.InvokeCommand.GetCommand('Microsoft.PowerShell.Management\Get-ChildItem', [System.Management.Automation.CommandTypes]::Cmdlet
                )
                if ($PSBoundParameters.Keys -contains ("File") -and $PSBoundParameters.Keys -notcontains ("Directory")) {					
                    $PSBoundParameters.Remove('File') | out-null
                    $scriptCmd = {& $wrappedCmd @PSBoundParameters | Where-Object { ! $_.PSIsContainer} }
                } 
		elseif ($PSBoundParameters.Keys -contains ("Directory") -and $PSBoundParameters.Keys -notcontains ("File")) {					
                    $PSBoundParameters.Remove('Directory') | out-null
                    $scriptCmd = {& $wrappedCmd @PSBoundParameters | Where-Object { $_.PSIsContainer} }
                }
		elseif ($PSBoundParameters.Keys -contains ("Directory") -and $PSBoundParameters.Keys -contains ("File")) {
			$PSBoundParameters.Remove('File') | out-null
			$PSBoundParameters.Remove('Directory') | out-null
			$scriptCmd = {& $wrappedCmd @PSBoundParameters }
		}
		else {					
                    $scriptCmd = {& $wrappedCmd @PSBoundParameters }
                }
                $steppablePipeline = $scriptCmd.GetSteppablePipeline($myInvocation.CommandOrigin)
                $steppablePipeline.Begin($PSCmdlet)
            } catch {
                throw
            }
        }

        process {
            try {
                $steppablePipeline.Process($_)
            } catch {
                throw
            }
        }
        end {
            try {
                $steppablePipeline.End()
            } catch {
                throw
            }
        }        
    }
}