PowerShell/GetEnumerator

I have a simple question:

Why the program below does not write 开发者_StackOverflow社区the whole array $lines? It is looping forever. I am really confused..

function Get-Current ($enumerator) {
    $line = $enumerator.Current
    return $line
}

$lines = @('a', 'b', 'c')
$enumerator = $lines.GetEnumerator()
$enumerator.Reset()

while ($enumerator.MoveNext()) {
    $line = Get-Current $enumerator
    "$line"     
}

It seems as though the expression:

$enumerator

unwinds the entire enumerator. For e.g.:

PS C:\> $lines = @('a', 'b', 'c')
PS C:\> $enumerator = $lines.GetEnumerator()
PS C:\> $enumerator.Reset()
PS C:\> $enumerator
a
b
c

So, when you try to pass your expression to the function, it is rendered invalid. The only workaround I can think of is to pass it as a PSObject like so:

function Get-Current ($val) {
    $val.Value.Current
}

$lines = @('a', 'b', 'c')
$enumerator = $lines.GetEnumerator()
$enumerator.Reset()

while ($enumerator.MoveNext()) {
    $line = Get-Current $(get-variable -name enumerator)
    $line
}

Don't know why MoveNext never returns false. This works

$lines = @('a', 'b', 'c')
$enumerator = $lines.GetEnumerator()

while ($enumerator.MoveNext()) {
    $enumerator.Current
}