function Prompt
{
    param([string] $prompt, $validationScript)
    $rv = $null
    do
    {
        try
        {
            $input = Read-Host -Prompt $prompt
            $rv = Invoke-Command $validationScript -ArgumentList $input
        } catch
        {
            Write-Host "Invalid input, try again"
        }
    } while (!$rv)
    $rv
}

$xxx = Prompt -Prompt "Enter integer" -validationScript {[Convert]::ToInt32($args[0], 10)}
$xxx