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Generic list and powershell

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I met with an accident recently riding my motorcycle and hence was unable to blog for some time. Here is my post after a brief break.

I wanted to create a generic list of my class in power shell. It was an interesting experience. Here is what I found.

 

When I tried to create a generic list of say type int it was straight forward ... well sort of ... the syntax was awkward, but still worked.

$list = New-Object "System.Collections.Generic.List``1[System.Int32]"

$list.Add(3)

$list

I wrote a sample assembly as below:

using System;

public class Sample

{

    public Sample() {}

    public void SampleMethod() { Console.WriteLine("Hello");}

 

}

Compiled this to sample.dll as csc /target:library sample.cs

[Reflection.Assembly]::LoadFrom("c:\Sample\Sample.dll")

Make sure if the assembly is loaded

[System.AppDomain]::CurrentDomain.GetAssemblies()

Now add the class Sample to the list. It gave me the error below.

$list = New-Object "System.Collections.Generic.List``1[Sample]"

New-Object : Cannot find type [System.Collections.Generic.List`1[Test]]: make sure the assembly containing this type is loaded.

At line:1 char:19 + $list = New-Object <<<< "System.Collections.Generic.List``1[Test]"

I am not sure why this is not working as the syntax is very similar to the one I had above for Int32. After some search and experimenting I figured out another way to get the generic list working.

$si = new-object Sample

$st = [Type] $si.GetType()

$base = [System.Collections.Generic.List``1]

$qt = $base.MakeGenericType(@($st))

$so = [Activator]::CreateInstance($qt)

$so.Add($si)

write-host $so

Sample

$so[0].SampleMethod()

Hello

Comments

  • Anonymous
    October 14, 2009
    Man, hope you're OK. I am also riding a bike and other people simply don't see us on the road. Nice post, will bookmark it for future reference.

  • Anonymous
    April 10, 2013
    Very good post, simple and effective !!