Is there a better way to check if a collection is empty before a foreach in PowerShell?

Question

I have part of a deploy PowerShell 2.0 script that copy a potential robots.dev.txt to robots.txt, if it doesn't exist don't do anything.

My original code was:

$RobotFilesToOverWrite= Get-ChildItem -Path $tempExtractionDirectory -Recurse -Include "robots.$Environment.txt"
    foreach($file in $RobotFilesToOverWrite)
    {
        $origin=$file
        $destination=$file -replace ".$Environment.","."

        #Copy-Item $origin $destination
    }

But, in a difference with C#, even if $RobotFilesToOverWrite is null, code is entering in the foreach.

So I had to surround everything with:

if($RobotFilesToOverWrite)
{
    ...
}

This is the final code:

$RobotFilesToOverWrite= Get-ChildItem -Path $tempExtractionDirectory -Recurse -Include "robots.$Environment.txt"
if($RobotFilesToOverWrite)
{
    foreach($file in $RobotFilesToOverWrite)
    {
        $origin=$file
        $destination=$file -replace ".$Environment.","."

        #Copy-Item $origin $destination
    }
}

I was wondering if there is a better way to achieve that?

EDIT: This problem seems to be fixed in PowerShell 3.0

Answer 1

# one way is using @(), it ensures an array always, i.e. empty instead of null
$RobotFilesToOverWrite = @(Get-ChildItem -Path $tempExtractionDirectory -Recurse -Include "robots.$Environment.txt")
foreach($file in $RobotFilesToOverWrite)
{
    ...
}

# another way (if possible) is not to use an intermediate variable
foreach($file in Get-ChildItem -Path $tempExtractionDirectory -Recurse -Include "robots.$Environment.txt")
{
    ...
}

Answer 2

quote from http://blogs.msdn.com/b/powershell/archive/2012/06/14/new-v3-language-features.aspx

ForEach statement does not iterate over $null

In PowerShell V2.0, people were often surprised by:

PS> foreach ($i in $null) { 'got here' } got here

This situation often comes up when a cmdlet doesn’t return any objects. In PowerShell V3.0, you don’t need to add an if statement to avoid iterating over $null. We take care of that for you.