Strange behavior with Powershell scriptblock variable scope and modules, any suggestions?

Question

NOTE: I\'m using PowerShell 2.0 on Windows Vista.

I\'m trying to add support for specifying build arguments to psake, but I\'ve run into some strange PowerShell var

Answer 1

It appears that the $message in the scriptblock passed in is tied to the global scope e.g.:

function Test { 
    param( 
        [Parameter(Position=0,Mandatory=0)] 
        [scriptblock]$properties = {} 
    ) 

    $defaults = {$message = "Hello, world!"} 

    Write-Host "Before running defaults, message is: $message" 

    . $defaults 

    #At this point, $message is correctly set to "Hellow, world!" 
    Write-Host "Aftering running defaults, message is: $message" 

    . $properties 

    #At this point, I would expect $message to be set to whatever is passed in, 
    #which in this case is "Hello from poperties!", but it isn't.   
    Write-Host "Aftering running properties, message is: $message" 

    # This works. Hmmm
    Write-Host "Aftering running properties, message is: $global:message" 
} 

Export-ModuleMember -Function "Test" 

Outputs:

Before running defaults, message is: 
Aftering running defaults, message is: Hello, world!
Executing properties, message is 
Aftering running properties, message is: Hello, world!
Aftering running properties, message is: Hello from properties!

This would appear to be a bug. I'll prod the PowerShell MVP list to see if I can confirm this.