Nesting C# object initialization in PowerShell

Question

I have a C# function (MyFunction(List<SafeInfo> securitySchema)). I'm trying to write a powershell script that will create the List<SafeInfo> object and pass it into MyFunction(List<SafeInfo>) via reflection. Reflection's all good in PowerShell, but I'm trying to figure out the correct way to transpose the creation of the argument object into PowerShell.

Here's asample C# object that can be used:

List<SafeInfo> schema = new List<SafeInfo>() {
    new SafeInfo("mySafe1", new SecurityInfo("key1", SecurityType.Key, "some description")),
    new SafeInfo("mySafe2", new SecurityInfo("key2", SecurityType.Combination, "another description")),
    new SafeInfo("mySafe3", SecurityInfo.Unsecured)
};

My PowerShell so far:

$schema = New-Object 'Collections.Generic.List[MyNamespace.SafeInfo]'
$schema.Add(New-Object('MyNamespace.SafeInfo', 'mySafe1', New-Object('MyNamespace.SecurityInfo', 'key1', SecurityType.Key, 'some description')))
$schema.Add(New-Object('MyNamespace.SafeInfo', 'mySafe2', New-Object('MyNamespace.SecurityInfo', 'key2', SecurityType.Combination, 'another description')))
$schema.Add(New-Object('MyNamespace.SafeInfo', 'mySafe3', [MyNamespace.SecurityInfo]::Unsecured))

Am I on the right track? What's the best way to create this nested object in PowerShell? Thanks!

Mathias R. Jessen · Accepted Answer · 2015-08-27 22:07:13Z

Am I on the right track?

Yes and no.

New-Object is a cmdlet, and cmdlet parameters are space-separated (and named) rather than comma-separated arguments like in C#.

Furthermore, with New-Object the type name and the argument list is two separate parameters

New-Object -TypeName 'MyNamespace.SafeInfo' -ArgumentList 'mySafe1',([MyNamespace.SecurityInfo]::Unsecured)

(notice how you can not resolve the static member Unsecured directly in the list, thus the () around)

You can't call a cmdlet directly inside a .NET method, but you can wrap the call in a subexpression ($()):

$schema.Add($(New-Object -TypeName 'MyNameSpace.SafeInfo' -ArgumentList 'mySafe1',$(New-Object -TypeName 'MyNameSpace.SafeInfo' -ArgumentList "key1", SecurityType.Key, "some description")))

If a parameter supports positional binding (as does -TypeName and -ArgumentList), you can omit the parameter name:

$schema.Add($(New-Object 'MyNameSpace.SafeInfo' 'mySafe1',$(New-Object 'MyNameSpace.SafeInfo' "key1",SecurityType.Key,"some description")))

Again, notice how the first parameter value ('MyNameSpace') and the second (the argument list) is separated by a space rather than a comma

With the above in mind, your examples become:

$schema = New-Object 'Collections.Generic.List[MyNamespace.SafeInfo]'
$schema.Add($(New-Object 'MyNamespace.SafeInfo' 'mySafe1',$(New-Object 'MyNamespace.SecurityInfo' 'key1',([MyNamespace.SecurityType]::Key),'some description')))
$schema.Add($(New-Object 'MyNamespace.SafeInfo' 'mySafe2',$(New-Object 'MyNamespace.SecurityInfo' 'key2',([MyNamespace.SecurityType]::Combination),'another description')))
$schema.Add($(New-Object 'MyNamespace.SafeInfo' 'mySafe3',([MyNamespace.SecurityInfo]::Unsecured)))

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