Start-job invoke function from different powershell - powershell

Question

In Powershell with the function Start-Job you can call functions if you initialize them beforehand.
$export_functions =
{
Function Log($message) {Write-Host $message}
Function MyFunction($message) {Log($message)}
}
$param1="Hello stack overflow!"
Start-Job -ScriptBlock {MyFunction $using:param1} -InitializationScript $export_functions -ArgumentList #($param1) | Wait-Job | Receive-Job
Would it be possible to use a 'global' function inside the script block as well?
So something like:
Function Log($message) {Write-Host $message}
$export_functions =
{
Function Log($message) {$Function:Log($message)}
Function MyFunction($message) {Log($message)}
}
$param1="Hello stack overflow!"
Start-Job -ScriptBlock {MyFunction $using:param1} -InitializationScript $export_functions -ArgumentList #($param1) | Wait-Job | Receive-Job
Or is that not intended after all?

Answer 1

One way to capture the function definition from the caller's scope (defined outside the initialization script block) is to use an expandable (double-quoted) string ("..."), i.e. string interpolation, and then use [scriptblock]::Create() to create a script block from the result.
You can combine this technique with defining the code you want to place directly inside the script block as usual:
Function Log($message) { Write-Host $message }
# Use string interpolation to capture the body of function Log ($function:Log)
$export_functions = [scriptblock]::Create(
"Function Log { $function:Log }`n" +
{
Function MyFunction($message) { Log $message }
}
)
Start-Job -InitializationScript $export_functions { Log 'hi1'; MyFunction 'hi2' } |
Receive-Job -Wait -AutoRemoveJob
Note the use of $function:Log to refer to the Log function's body, which is an example of namespace variable notation.