How do I share variables among scripts in Powershell?

Question

I have difficulty trying to find an answer that solves this issue online.

I have a script which runs all my other scripts in a particular order.

$x=0;
$z=0;
cd *file path* ;
.\filename1.ps1 ; write-host "$x text $z text";
.\filename2.ps1 ; write-host "$x text $z text";

In each of these scripts I have options that will add 1 to either variable $x or variable $z

$a=Read-Host
if ($a -eq "Option One") {$x = $x+1}
elseif ($a -eq "Option Two") {$z = $z+1}
else {Write-Host "Not a valid option" ; .\filenameX.ps1}

The issue is that the script that runs all these scripts won't recognise the change in variable. How do I fix this?

Answer 1

The naïve answer is to "dot-source" these scripts, i.e. to invoke them with operator . 

Using .  executes the scripts in the caller's variable scope, so that top-level modifications of $x an $z will be visible even after .\filename1.ps1 and .\filename2.ps1 have completed.

# Note the `. ` preceding the file path - the space after "." is mandatory
. .\filename1.ps1 ; "$x text $z text"
. .\filename2.ps1 ; "$x text $z text"

Note, however, that all top-level variables created or modified in . -invoked scripts will be visible to the caller.

For more on variable scopes in PowerShell, see this answer.

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Better encapsulated options are to either (a) output modified values or, less commonly, (b) use of [ref] parameters to pass by-reference variables to scripts - whose parameters must be declared and assigned to accordingly.