Powershell: PSCustomObject array as parameter in function gets changed unexpectedly - arrays

Question

In the simplified PS code below, I don't understand why the $MyPeople array gets changed after calling the changeData function. This array variable should just be made a copy of, and I expect the function to return another array variable into $UpdatedPeople and not touch $MyPeople:
function changeData {
Param ([PSCustomObject[]]$people)
$changed_people = $people
$changed_people[0].Name = "NEW NAME"
return $changed_people
}
# Original data:
$Person1 = [PSCustomObject]#{
Name = "First Person"
ID = 1
}
$Person2 = [PSCustomObject]#{
Name = "Second Person"
ID = 2
}
$MyPeople = $Person1,$Person2
"`$MyPeople[0] =`t`t" + $MyPeople[0]
"`n# Updating data..."
$UpdatedPeople = changeData($MyPeople)
"`$UpdatedPeople[0] =`t" + $UpdatedPeople[0]
"`$MyPeople[0] =`t`t" + $MyPeople[0]
Console output:
$MyPeople[0] = #{Name=First Person; ID=1}
# Updating data...
$UpdatedPeople[0] = #{Name=NEW NAME; ID=1}
$MyPeople[0] = #{Name=NEW NAME; ID=1}
Thanks!

Answer 1

PSObject2 = PSObject1 is not a copy but a reference. You need to clone or copy the original object using a method designed for that purpose.
function changeData {
Param ([PSCustomObject[]]$people)
$changed_people = $people | Foreach-Object {$_.PSObject.Copy()}
$changed_people[0].Name = "NEW NAME"
return $changed_people
}
The technique above is simplistic and should work here. However, it is not a deep clone. So if your psobject properties contain other psobjects, you will need to look into doing a deep clone.

Answer 2

We can clone the PSCustomObject. We will create a new PSObject and enumerate through the psobject given as parameter and add them one by one to the shallow copy.
function changeData {
Param ([PSCustomObject[]]$people)
$changed_people = New-Object PSobject -Property #{}
$people.psobject.properties | ForEach {
$changed_people | Add-Member -MemberType $_.MemberType -Name $_.Name -Value $_.Value
}
$changed_people[0].Name = 'NEW NAME'
return $changed_people
}
Or use another method by #AdminOfThings