How to do it...

Install and start PowerShell Core and execute the following steps:

1. Execute the following code block:

$outerScope = 'Variable outside function'

function Foo
{
    Write-Host $outerScope
    $outerScope = 'Variable inside function'
    Write-Host $outerScope
}

Foo
Write-Host $outerScope

You should see the following output:

1. Modify the code a little bit to use scope modifiers like private, script, and local and try it again:

 <#
  By explicitly using scopes, you can alter the state of virtually any variable
  The following scopes are available. Inner scopes can access variables from outer scopes
  global: The outermost scope, i.e. your current session
  script: The scope of a script or module
  local: The scope inside a script block
  private: In any scope, hidden from child scopes
  using: This one is special.
#>
$outerScope = 'Variable outside function'
$private:invisible = 'Not visible in child scopes'

function Foo
{
    Write-Host $outerScope
    $script:outerScope = 'Variable inside function'
    $local:outerScope = 'Both can exist'
    Write-Host "Private variable content can't be retrieved: $invisible"
    Write-Host $outerScope
}

Foo
Write-Host $outerScope

This time, you'll notice that you can create multiple variables with the same name in different scopes.

1. Try the following code next, to see how the using scope works:

$processName = 'pwsh'
$credential = New-Object -TypeName pscredential -ArgumentList 'user',$('password' | ConvertTo-SecureString -AsPlainText -Force)
Start-Job -ScriptBlock { Get-Process -Name $processName} | Wait-Job | Receive-Job # Error
Start-Job -ScriptBlock { Get-Process -Name $using:processName} | Wait-Job | Receive-Job # Works
Start-Job -ScriptBlock { $($using:credential).GetNetworkCredential().Password } | Wait-Job | Receive-Job # Works as well

As you have seen in the output of the previous cmdlet, the using scope allows access to variables from within a script block.