I try to add an existing function as a method to a new created object. Writing an inline function works:

$myObject | Add-Member ScriptMethod -name Calc -value{param([int]$a,[int]$b;$a $b}

Having a function:

function get-Calc{param([int]$a,[int]$b) $a  $b}

this doesn't work:

$myObject | Add-Member ScriptMethod -name Calc -value(get-Calc)

CodePudding user response：

Defined functions are stored in the special function:\ drive.

To reference a function definition using variable syntax:

$myObject | Add-Member ScriptMethod -name Calc -Value ${function:get-Calc}

CodePudding user response：

You could also do it passing a script block as -Value, see the Constructor for PSScriptMethod Class.

function Get-Calc { param([int]$a, [int]$b) $a   $b }

$myObject = [pscustomobject]@{
    A = 1
    B = 2
}

# If you're referencing the existing Properties of the Object:
$myObject | Add-Member ScriptMethod -Name MyMethod1 -Value {
    Get-Calc $this.A $this.B
}

# If you want the Instance Method to reference the arguments being passed:
$myObject | Add-Member ScriptMethod -Name MyMethod1 -Value {
    param($a, $b)
    Get-Calc $a $b
}

# This is another alternative as the one above:
$myObject.PSObject.Methods.Add(
    [psscriptmethod]::new('MyMethod3', {param($a, $b) Get-Calc $a $b})
)

$myObject.MyMethod1()
$myObject.MyMethod2(1,2)
$myObject.MyMethod3(3,4)

CodePudding user response：

There are 2 problems with your example that do not work.

• You are not passing Get-Calc as a scriptblock (The expected value for a scriptmethod is a scriptblock)
• You are not passing your expected parameters

Instead of

$myObject | Add-Member ScriptMethod -name Calc -value(get-Calc)

Do this:

$myObject | Add-Member ScriptMethod -name Calc3 -value {param([int]$a,[int]$b) get-Calc -a $a -b $b}