List<T> in PowerShell?

Question

Hi,
Looking to create a List<T> in PowerShell but struggling to find out how to add properties to it. This is what I have so far but
I get an error message on Add or AddRange.

using namespace System.Collections.Generic  
  
class Errors   
{  
    [string] $Y   
    [string] $X   
}  
  
  
Clear-Host  
  
  
$Errors = New-Object List[Errors]  
$Errors.Add(New-Object -TypeName Errors -ArgumentList "0", "1")  
$Errors.Add("1", "2")  
$Errors.AddRange("3", "4")  
$Errors  

This C# example shows what I'm trying to achieve

Answer 1

In general you shouldn't need to use List<T> directly in PS. Unless you're doing interop with a .NET type that requires it then just stick with PS arrays.

[System.Collections.Generic.List[Errors]] $errors = @()

# Or
$errors = New-Object System.Collections.Generic.List[Errors]

To add you need an Errors object.

$item = New-Object -TypeName Errors
$item.X = 1
$item.Y = 2

$errors += $item

# Or...
$errors.Add($item)

Your first add won't work because the Errors type doesn't have a constructor that accepts 2 parameters. The second add doesn't work because the Add function requires an Errors.

Answer 2

Hi @Michael Taylor

Thanks for your response, I got it working as below.

Clear-Host  
  
class Errors   
{  
    [int] $Y   
    [int] $X   
}  
  
$errors = New-Object System.Collections.Generic.List[Errors]  
  
  
[Errors] $item1 = New-Object -TypeName Errors  
# [Errors] $item2 = New-Object Errors   
  
$item1.X = 1  
$item1.Y = 2  
$errors.Add($item1)  
$errors.Add($item1)  

Was wondering if there's a way to create and assign $item1 in the .Add arguments list?

Thanks

Answer 3

Thanks @Michael Taylor for your help :-)