Powershell scripting : Why is this function not able to access a global variable

Question

i have a script, let's say script1 that calls a function abc from script2. Below is script2 :-

$Global:splat2 
function xyz ()
{
    Write-Host "in xyz"
    Write-Host "$Global:splat2"
}
function abc ([System.Collections.ArrayList] $splat)
{
    $Global:splat2 = $splat
    Write-Host "in abc"
    Write-Host "$Global:splat2"
    $func = (Get-Command -Type Function xyz)
    $wholeFuncDef = 'Function ' + $func.Name + " {`n" + $func.Definition + "`n}"

    Start-Process powershell -args '-noprofile', '-noexit', '-EncodedCommand', `([Convert]::ToBase64String([Text.Encoding]::Unicode.GetBytes("$wholeFuncDef; xyz")))
    
}

The function abc is called from script 1 (some value was assigned to $splat):

abc $splat

The problem is that only function abc prints the value for $splat2 while as in function xyz, $splat2 is empty. I was expecting that function xyz should also have the value for $splat2 since it's a global variable.

Looking at this, I see nothing wrong, nor can I replicate this issue on PS 5.1. What PowerShell version are you using btw? — Abraham Zinala, Mar 07 '22 at 21:42
sorry, i have edited the question now. Actuallly the function xyz is being called in a separate console — korra, Mar 07 '22 at 22:03

mklement0 · Accepted Answer · 2022-03-07T23:09:08.783

Global variables are limited to a given session, i.e. a PowerShell runspace (thread) inside a given process.

Using Start-Process with powershell.exe invariably creates a new session, in a new process, which knows nothing about the caller's variables (except for inheriting environment variables by default).

You'll have to pass any values from the caller's scope explicitly to such a separate session.

Options:

Incorporate values from the caller's scope as a variable-assignment statements into the (Base64-encoded) command string passed to -EncodedCommand
A simple alternative is indeed to use an aux. environment variable.

Caveat re data types:

If you use an environment variable, its value is invariably a string.
If you incorporate a variable assignment into the command string, you can express more data types, but are limited to those that can be expressed as literals in PowerShell (unless you include a constructor call based on a literal, if feasible).
Supporting more data types - but not all - is possible with the - undocumented as of this writing - -EncodedArguments parameter; see this answer.

Powershell scripting : Why is this function not able to access a global variable

1 Answers1