What is the syntax to subscribe to an object's static event in PowerShell?

Question

Register-ObjectEvent looks for a object instance in the required parameter InputObject. What is the syntax for an object's static (Shared) event?

UPDATE: Correct syntax for TimeChanged:

$systemEvents = [Microsoft.Win32.SystemEvents]
$timeChanged = Register-ObjectEvent -InputObject $systemEvents
-EventName 'TimeChanged' -Action { Write-Host "Time changed" }

Unfortunately, the SystemEvents will not be signaled in PowerShell ISE. Here's a sample using an object's staic event that works everywhere:

$networkInformation = [System.Net.NetworkInformation.NetworkChange];
$networkAddressChanged = Register-ObjectEvent -InputObject $networkInformation 
-EventName 'NetworkAddressChanged' 
-Action { Write-Host "NetworkAddressChanged event signaled" }

There is a message loop running in PowerShell, but you need to run as an admin to access it. — Steven Murawski
– Steven Murawski, Commented Mar 2, 2010 at 2:08

Steven Murawski · Accepted Answer · 2010-03-01 23:01:43Z

10

+150

If you assign a static type to a variable, you can subscribe to static events.

For example:

$MyStaticType = [MyStaticNamespace.MyStaticClass]
Register-ObjectEvent -InputObject $MyStaticType -EventName MyStaticEvent -Action {Write-Host "Caught a static event"}

To find any static events a type may have, you can use Get-Member with the -Static switch

[MyStaticNamespace.MyStaticClass] | get-member -static -membertype event

EDIT: I did notice when trying to access [Microsoft.Win32.SystemEvents] events, that I needed to be running in an elevated prompt (on Vista and above) in order to access the messages.

edited Mar 1, 2010 at 23:01

answered Mar 1, 2010 at 22:26

Steven Murawski

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Keith Hill · Accepted Answer · 2010-03-02 01:11:28Z

3

Steven's got the right answer so no need to vote on this (vote on his instead). I just wanted to post a sample snippet that folks can use to play around with static events such that you don't have to find a BCL static event that's easy to fire. :-)

$src = @'
using System;

namespace Utils {
public static class StaticEventTest 
{
    public static event EventHandler Fired;

    public static void RaiseFired()
    {
        if (Fired != null) 
        { 
            Fired(typeof(StaticEventTest), EventArgs.Empty); 
        }
    }
}}
'@

$srcId = 'Fired'

Add-Type -TypeDefinition $src

Unregister-Event -SourceIdentifier $srcId -ea 0

$id = Register-ObjectEvent ([Utils.StaticEventTest]) Fired `
          -SourceIdentifier $srcId -Action {"The static event fired"}

[Utils.StaticEventTest]::RaiseFired()

while (!$id.HasMoreData) { Start-Sleep -Milliseconds 250 }

Receive-Job $id

answered Mar 2, 2010 at 1:11

Keith Hill

204k44 gold badges370 silver badges377 bronze badges

1 Comment

dxiv Over a year ago

Thanks for this. I took the liberty of borrowing much of the snippet in my question here.

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