Create a wrapper for functions in PowerShell

Question

I want to wrap a function, that is to create a new function such that it would automatically pass some arguments to the old function, like Python's partial functions. The arguments passed are the ones defined in the callee and not the caller. The important thing is that I don't want to refer to each of them explicitly (define them twice).

That is really done to save typing-in the same flags to complicated functions while allowing customization.

For example, in Python, I would do:

call_with_x=partial(call,x=1)

Or maybe use **kw and pass it to the callee in some cases.

---

This is my best try (based on Wrapper function in PowerShell: Pass remaining parameters):

function Let
{
    [CmdletBinding()]
Param([parameter(mandatory=$true, position=0)][string]$Option,
    [parameter(mandatory=$false, position=1, ValueFromRemainingArguments=$true)]$Remaining)
Get @Remaining
}

function Get
{
    [CmdletBinding()]
        Param([parameter(mandatory=$false, position=0)][string]$OptionA,
[parameter(mandatory=$true, position=1)][string]$OptionB)
Write-Host $OptionA, $OptionB
}

But Let -Option c -OptionA 1

Prints -OptionA 1 which is obviously not what I intended.

Answer 1

That was hard! For this you would need to add a bit of code in DynmaicParams and begin section of the function.

It might be possible to do it in an Attribute

function x{
[WrapperFor(y)]

Might do it Later.

function Get
{
    [CmdLetBinding()]
        Param([parameter(mandatory=$false, position=0)][string]$OptionA,
[parameter(mandatory=$false, position=1)][string]$OptionB)
Write-Host "opta",$OptionA
Write-Host "optb",$OptionB
}


function Let
{
    [CmdletBinding()]
Param([parameter(mandatory=$true, position=0)][string]$Option,[parameter(mandatory=$false, position=0)][string]$OptionB)


DynamicParam {
AddWrapper -For "Get" -To "Let"
}
Begin { 
    
   $params = GetRestOfParams "Get" $PSBoundParameters
}
Process {
    Get @params 
}
}

Needed code:

using namespace System.Management.Automation
function Empt
{
    [CmdletBinding()]
        Param([parameter(mandatory=$true, position=0)][string]$aaaa)
    1
}

function AddWrapper([parameter(mandatory=$true, position=0)][string]$For,[parameter(mandatory=$true, position=1)][string]$To) 
{
    $paramDictionary = [RuntimeDefinedParameterDictionary]::new()
    $paramset= $(Get-Command $For).Parameters.Values | %{[System.Management.Automation.RuntimeDefinedParameter]::new($_.Name,$_.ParameterType,$_.Attributes)}
    $paramsetlet= $(Get-Command empt).Parameters.Keys 
    $paramsetlet+= $(Get-Command $To).ScriptBlock.Ast.Body.ParamBlock.Parameters.Name | %{ $_.VariablePath.UserPath }
    $paramset | %{ if ( -not ($paramsetlet -contains $_.Name) ) {$paramDictionary.Add($_.Name,$_)}}
    return $paramDictionary
}
function GetRestOfParams($dst,$params)
{
    $dstorgparams=$(Get-Command $dst).Parameters.Keys
    $z= $params
    $z.Keys | %{ if ( -not ($dstorgparams -contains $_) ) {$z.Remove($_)} } | Out-Null
    return $z
}