Powershell console issue with function executing in action of Register-ObjectEvent

Question

Works fine in powershell ISE, but in console I get:

The term 'MainAction' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.

How to fix?

function MainAction () {
    $test = "123"
    Write-Host $test
}

MainAction

$action = {
    try {
        Write-Host in action
        MainAction
    } catch {
        Write-Host $Error    
        $timer.Stop()
        Unregister-Event thetimer
    }
}

$timer = New-Object Timers.Timer    
Register-ObjectEvent -InputObject $timer -EventName elapsed `
                     -SourceIdentifier thetimer -Action $action -OutVariable out
$timer.Interval = 5000
$timer.AutoReset = $true
$timer.Start()

EDIT:

I found that I can use profile to store function definitions. To create profile use:

New-Item -path $profile -itemType file -force

But I'am still intrested why powershell ISE don't need profile to store and use functions in action of Register-ObjectEvent.

you right, this works and more convinient than profile, thank you — Lavandil
– Lavandil, Commented Feb 11, 2017 at 11:14

user4003407 · Accepted Answer · 2017-02-11 11:39:44Z

7

When you register -Action with Register-ObjectEvent, PowerShell will create new dynamic module to host the action. Thus, as result of that, only global scope is shared between event handler and rest of the code. So, you should put all needed functions in global scope:

function global:MainAction {
    Write-Host 'Do something'
}

$Action = { MainAction }

$Timer = New-Object Timers.Timer
$EventJob = Register-ObjectEvent -InputObject $Timer -EventName Elapsed -Action $Action

$Timer.Interval = 5000
$Timer.AutoReset = $true
$Timer.Start()

Or explicitly add them in scope of that dynamic module, created by PowerShell:

$Action = { MainAction }

$Timer = New-Object Timers.Timer
$EventJob = Register-ObjectEvent -InputObject $Timer -EventName Elapsed -Action $Action

. $EventJob.Module {
    function MainAction {
        Write-Host 'Do something'
    }
}

$Timer.Interval = 5000
$Timer.AutoReset = $true
$Timer.Start()

answered Feb 11, 2017 at 11:39

user4003407

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1 Comment

Lavandil Over a year ago

I also want to add now that it can be convinient to use dynamic module to store your functions and variables if they must be accessible from main thread too.

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