Array changes when object taken from array gets changed

Not sure if this is a bug or if I just don’t understand the behavior: You start with an array with objects in them. You assign a variable for one of these objects. When you change that object, the original array is changed as well.

Steps to reproduce

Example1:

# Set up an array with two objects in it
$SourceArray = @(
    [PSCustomObject]@{
        Name = "Value1"
        property1 = "blieb"
        property2 = "blaab"
        property3 = "bloeb"
    }
    [PSCustomObject]@{
        Name = "Value2"
        property1 = "blieb"
        property2 = "blaab"
        property3 = "bloeb"
    }
)

# Create a variable based on an object in the array
$IssueObject = $SourceArray[0]
# Add a member to the object
$IssueObject | Add-Member -MemberType NoteProperty -Name "ExtraProperty" -Value "blaib" -Force
# So we have the object with an extra property
$IssueObject

# Now if we call the same object from the source array,
# I wouldn't expect an extra member, as I created a new variable for the changed object
$sourcearray[0]
# Turns out the object in the variable has changed as well??


# Looking further: Let's create the variable again but add | select-object *
$IssueObject = $sourcearray[1]  | Select-Object *
# Do the same thing as before
$IssueObject | Add-Member -MemberType NoteProperty -Name "ExtraProperty" -Value "blaib" -Force
$IssueObject 

# Call the object form the array again
$SourceArray[1]
# And results are as expected: without the extra member.

Example2 (run as admin to reproduce):

# Collect all the services in an array
$Services = Get-Service

# Collect the status of the time service
$Services | Where-Object {$_.Name -eq "W32Time"}

# Save the Time service in a new variable
$Time = $Services | Where-Object {$_.Name -eq "W32Time"}

# Start the time service (or stop if it was already started)
$Time | Start-Service

# The time service is now running. But I did not touch the Services variable.
# So I would expect the status in the Services Variable to still be Stopped.
# But it now comes back as running...
$Services | Where-Object {$_.Name -eq "W32Time"}

Expected behavior

I would expect the array to change when I define a new variable to work with. I would also not expect a difference when Select-Object is used.

Actual behavior

Environment data

Tested on multiple devices (all Windows), on PowerShell 7.1.0, 7.2.0 as well as Windows PowerShell

Name                           Value
----                           -----
PSVersion                      7.1.0
PSEdition                      Core
GitCommitId                    7.1.0
OS                             Microsoft Windows 10.0.18363
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Name                           Value
----                           -----
PSVersion                      7.2.0-preview.2
PSEdition                      Core
GitCommitId                    7.2.0-preview.2
OS                             Microsoft Windows 10.0.18363
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

[SteveL-MSFT]

I agree with @SeeminglyScience that OP posted what they thought was unexpected behavior, so open an issue (if one doesn’t already exist) is the right thing. I appreciate @mklement0 responding with correct information and pointers. In general, we are considering enabling GitHub Discussions for general type of discussions not specific to the code of this project, but we won’t get to that til next year.

On the internet where all you see is text and no body language, sometimes one may presume the worst, but many times I find that was not the intent (which is clear in this case by @mklement0’s response later in the thread). Overall, it looks like everything worked out and I appreciate the discussion.

[Ba4bes]

Ok, few responses:

• The explanation and provided link is very clear, thank you for that.
• The recommendation did feel a bit reprimanding and I’m glad that was cleared up.
• I posted here as I thought this could be a bug, or at least unwanted behavior. I personally find this very counter-intuitive. The two examples here came from two different people who were as confused as I was. So even if it isn’t a bug, I thought it was useful to be mentioned here as behavior that raises questions.

As my wondering has been cleared up I will close this issue, thank you all for your responses