Implementing IEnumerator<T> in PowerShell

You Need To Implement Non-Generic.md

In order to implement IEnumerator<T> you have to explicitly implement the Current member for IEnumerator<T> and IEnumerator ... but PowerShell won't let you have two different implementations of the same property, nor will it let you explicitly implement an interface member. So we do one at a time, like this:

First, make a non-generic IEnumerator, but implemented with the type you want in the end:

    class __Generator : System.Collections.IEnumerator {
        [int]$Actual = 0

        [object]get_Current() {
            return $this.Actual
        }

        [bool] MoveNext() {
            $this.Actual = Get-Random
            return $true
        }

        [void] Reset() {
            $this.Actual = 0
        }

        [void] Dispose() {
            # Do nothing
        }
    }

Then, you implement the specific generic type:

    class Generator : __Generator, System.Collections.Generic.IEnumerator[int] {
        [int]get_Current() {
            return $this.Actual
        }
    }

Now you can actually use the generator class however you like:

    [Generator]::new() | Select -First 5