Powershell: passing parameters to functions stored in variables - powershell

Question

I'm trying to get a simple working example of using functions inside of jobs. I've managed to pass my function into the scriptblock used for my job, but I can't seem to get parameters to the function.
# concurrency
$Logx =
{
param(
[parameter(ValueFromPipeline=$true)]
$msg
)
Write-Host ("OUT:"+$msg)
}
# Execution starts here
cls
$colors = #("red","blue","green")
$colors | %{
$scriptBlock =
{
Invoke-Expression -Command $args[1]
Start-Sleep 3
}
Write-Host "Processing: " $_
Start-Job -scriptblock $scriptBlock -args $_, $Logx
}
Get-Job
while(Get-Job -State "Running")
{
write-host "Running..."
Start-Sleep 2
}
# Output
Get-Job | Receive-Job
# Cleanup jobs
Remove-Job *
Here's the output:
Processing: red
Id Name State HasMoreData Location Command
-- ---- ----- ----------- -------- -------
175 Job175 Running True localhost ...
Processing: blue
177 Job177 Running True localhost ...
Processing: green
179 Job179 Running True localhost ...
179 Job179 Running True localhost ...
177 Job177 Running True localhost ...
175 Job175 Running True localhost ...
Running...
Running...
OUT:
OUT:
OUT:
So as evidenced by the OUT: x3 in the output my function is getting called, but I haven't found any syntax that allows me to get the parameter to the function. Thoughts?
EDIT:
Note in Shawn's observation below and my response I tried using functions as variables because using a traditional function does not seem to work. If there is a way to get that working I'd be more than happy to not have to pass my functions around as variables.

Answer 1

The answer is to use the initializationscript parameter of Start-Job. If you define all your functions in a block and pass the block they become available.
Solution was found in this post:
How do I Start a job of a function i just defined?
Here is my example from before, now working:
# concurrency
$func = {
function Logx
{
param(
[parameter(ValueFromPipeline=$true)]
$msg
)
Write-Host ("OUT:"+$msg)
}
}
# Execution starts here
cls
$colors = #("red","blue","green")
$colors | %{
$scriptBlock =
{
Logx $args[0]
Start-Sleep 9
}
Write-Host "Processing: " $_
Start-Job -InitializationScript $func -scriptblock $scriptBlock -args $_
}
Get-Job
while(Get-Job -State "Running")
{
write-host "Running..."
Start-Sleep 2
}
# Output
Get-Job | Receive-Job
# Cleanup jobs
Remove-Job *

Answer 2

If you do not prefix your function name with keyword function, PowerShell does not know to treat it as such. As you have written your script it is basically a variable with some special text in it. Which as your output shows it is only executing the commands it recognizes within that variable's content: Write-Host "OUT:".
Using the correct syntax will tell PowerShell it is a function and that you have variables to pass into it that you need executed:
function Logx
{
param(
[parameter(ValueFromPipeline=$true)]
$msg
)
Write-Host ("OUT:"+$msg)
}
Then when you call it within your script you will just use Logx

Answer 3

Got this far. Have to run out, will try back later.
PS: What is getting passed at args[1], I am getting a lot of red,
CategoryInfo : InvalidData: (:) [Invoke-Expression], ParameterBindingValidationException
+ FullyQualifiedErrorId : ParameterArgumentValidationErrorNullNotAllowed,Microsoft.PowerShell.Commands.InvokeExpressionCommand
here is what I've managed so far.
# concurrency
$Logx =
{
param(
[parameter(ValueFromPipeline=$true)]
$msg
)
Write-Host ("OUT:"+$msg)
}
# Execution starts here
cls
$colors = #("red","blue","green")
$colors | %{
& $scriptBlock =
{ Invoke-Expression -Command $args[1]
Start-Sleep 3
}
Write-Host "Processing: " $_
Start-Job -scriptblock $scriptBlock -ArgumentList #($_, $Logx)
}
# Get-Job
while(Get-Job -State "Running")
{
write-host "Running..."
Start-Sleep 2
}
# Output
Get-Job | Receive-Job
# Cleanup jobs
Remove-Job *