Passing through -Verbose status to module cmdlets

powershell, powershell-module

Solution

There is a variable named $VerbosePreference you can check to see how Verbose output should be handled. However, scripts loaded into a separate scope is giving you the issues. If you read the `Get-Help about_scopes`, you'll see:

Script: The scope that is created while a script file runs. Only the commands in the script run in the script scope. To the commands in a script, the script scope is the local scope.

You can add the script to the current scope instead using dot source notation. From the same help file, below the heading Using Dot Source Notation with Scope it is stated that:

Scripts and functions follow all the rules of scope. You create them in a particular scope, and they affect only that scope unless you use a cmdlet parameter or a scope modifier to change that scope.

But, you can add a script or function to the current scope by using dot source notation. Then, when a script runs in the current scope, any functions, aliases, and variables that the script creates are available in the current scope.

I suggest reading up more about scopes in the `Get-Help about_scopes` help chapter.

For a quick test of whether this works or not:

[CmdletBinding()]
PARAM()

New-Module -Name TempModule -ScriptBlock {
    function Show-ModuleVerbosePreference
    {
        [CmdletBinding()]
        PARAM()

        Write-Host "Verbose preference in module function: $VerbosePreference"
    }
} | Out-Null

function Show-ScriptVerbosePreference
{
    [CmdletBinding()]
    PARAM()

    Write-Host "Verbose preference in script function: $VerbosePreference"
}

Show-ScriptVerbosePreference
Show-ModuleVerbosePreference</pre>

And if we try to call this script file using different methods we get the following output:

PS C:\> .\verbosity.ps1
Verbose preference in script function: SilentlyContinue
Verbose preference in module function: SilentlyContinue

PS C:\> .\verbosity.ps1 -Verbose
VERBOSE: Exporting function 'Show-ModuleVerbosePreference'.
VERBOSE: Importing function 'Show-ModuleVerbosePreference'.
Verbose preference in script function: Continue
Verbose preference in module function: SilentlyContinue

PS C:\> . .\verbosity.ps1
Verbose preference in script function: SilentlyContinue
Verbose preference in module function: SilentlyContinue

PS C:\> . .\verbosity.ps1 -Verbose
VERBOSE: Exporting function 'Show-ModuleVerbosePreference'.
VERBOSE: Importing function 'Show-ModuleVerbosePreference'.
Verbose preference in script function: Continue
Verbose preference in module function: Continue

So by using dot source notation we have added the script scope into the current scope which seems to make the VerbosePreference setting visible in the module method as well.

Problem

I have a PowerShell module that encapsulates a number of commonly-used business functions. It's not generally called from the console; rather, its functions are called by automated deployment and management scripts that import the module. The module incorporates a logging function that writes to both a centralised logging location. I'd also like to hook into the Write-Verbose functionality to write to the console as well. ``` #'Start Script.ps1 #'---------------- Import-Module Corporate Write-Logger 'Foo' ``` My restriction is that - from within the Corporate PowerShell module - I need to determine whether Script.ps1 has been called with the `-Verbose` parameter. Ideally, I would like the determination code entirely within the module itself. Here's an example: ``` [CmdletBinding()] Param () New-Module -Name TempModule -ScriptBlock { function Test-ModuleVerbose() { [CmdletBinding()] Param () PROCESS { $vb = ($PSCmdlet.MyInvocation.BoundParameters['Verbose'] -eq $true) Write-Host ("1: Module verbose preference: " + ($PSCmdlet.MyInvocation.BoundParameters['Verbose'] -eq $true)) Write-Host ("2: Module verbose preference: " + $Script:VerbosePreference) Write-Host ("3: Module verbose preference: " + $VerbosePreference) } } } | Out-Null function Test-Verbose() { [CmdletBinding()] Param () PROCESS { Write-Host ("Verbose preference: $VerbosePreference") Test-ModuleVerbose } } Test-Verbose ``` Save the above as test.ps1. When invoked from the console: ``` PS C:\temp> .\test.ps1 Verbose preference: SilentlyContinue 1: Module verbose preference: False 2: Module verbose preference: 3: Module verbose preference: SilentlyContinue PS C:\temp> .\test.ps1 -Verbose VERBOSE: Exporting function 'Test-ModuleVerbose'. VERBOSE: Importing function 'Test-ModuleVerbose'. Verbose preference: Continue 1: Module verbose preference: False 2: Module verbose preference: 3: Module verbose preference: SilentlyContinue ``` As you can see, the $VerbosePreference variable is not available from within the module. Is there a way of picking up from within the module whether the calling script has been invoked with the `-Verbose` flag?

Original source