reusing variables in foreach loop - powershell

Question

Realizing it probably it may not be best practices, is there any other reason to not reuse the current item variable in a foreach as such:
foreach ($a in $something)
{Write-host $a}
.
.
.
foreach ($a in $somethingelse)
{Write-host $a}
In other words, is it always going to be best to in that second case use a different variable ($b?)

Answer 1

As briantist mentions this is fine. However when I do a foreach loop I tend to keep it specified to whatever you're taking it from. I find this will make it easier to comprehend further down the line.
#Example 1
foreach ($item in $array)
{Write-Host $item}
#Example 2
foreach ($user in $userList)
{Write-Host $user}
#Example 3
foreach ($breed in $dogBreed)
{Write-Host $breed}

Answer 2

There's nothing wrong with that. The variable $a will always be set to the current item inside the foreach loop's body.

Answer 3

One reason why this isn't a idea is that variable $a retains it's value (within the assigned scope) until it is reassigned. That may not sound like a big issue, but occasionally PowerShell does something unexpected and it just isn't worth the time troubleshooting to figure something like that out. Consider this function:
function reuse-vars {
$arrayA = 0..3
$arrayB = 10..13
$arrayC = 20..23
foreach ( $a in $arrayA ){
Write-Host "`$a is $a"
Write-Host "`$b is $b"
Write-Host "`$c is $c"
}
foreach ( $b in $arrayB ){
Write-Host "`$a is $a"
Write-Host "`$b is $b"
Write-Host "`$c is $c"
}
foreach ( $c in $arrayC ){
Write-Host "`$a is $a"
Write-Host "`$b is $b"
Write-Host "`$c is $c"
}
}
$a will retain the value from the last foreach iteration until it is reassigned, that includes within nested foreach or if they are in series.
C:\> reuse-vars
$a is 0
$b is
$c is
$a is 1
$b is
$c is
$a is 2
$b is
$c is
$a is 3
$b is
$c is
$a is 3
$b is 10
$c is
$a is 3
$b is 11
$c is
$a is 3
$b is 12
$c is
$a is 3
$b is 13
$c is
$a is 3
$b is 13
$c is 20
$a is 3
$b is 13
$c is 21
$a is 3
$b is 13
$c is 22
$a is 3
$b is 13
$c is 23
It may not matter depending on what you're doing but the possibility for this to cause an issue makes it worthwhile to dream up a different variable name for each foreach (like $b).

Answer 4

I agree with the others that this should work just fine, but that using different names is better practice.
However, if you're paranoid you can always clear or delete the variable manually between the loops:
foreach ($a in $something)
{Write-host $a}
.
$a = $null;
.
foreach ($a in $somethingelse)
{Write-host $a}
Or:
foreach ($a in $something)
{Write-host $a}
.
Remove-Variable -Name a;
.
foreach ($a in $somethingelse)
{Write-host $a}