Passing Reference Type Parameter in Powershell

Question

 function test1{
     param([System.Collections.ArrayList]$x
     )
     $x.Add(\"Test1Add\")
     write \"in Test1 $x\"
 }
$x=New-Object System.Collections.ArrayList
         


        

Answer 1

Use Reference variables:

  $x=New-Object System.Collections.ArrayList
  function test( [ref][System.Collections.ArrayList]$x) { $x.value.Add($(get-random)) }
  test ([ref]$x)
  test ([ref]$x)
  $x

EDIT

I misunderstood the question, you wanted the opposite. The result is the same in above case but not for value types. If you want above function not to change the referenced object you need to clone it inside the function. There may be a Clone function, but in some cases you will have to manually create the clone. In this case there is such method so you can add $x=$x.Clone() at the start of the above function to get the desired result.

Value types are passed as value and other things are passed as reference. The easiest way to check if var is of ValueType is to do $var.GetType().IsValueType.