Question

By default, any named function that has the [CmdletBinding()] attribute accepts the -debug and -verbose (and a few others) parameters and has the predefined $debug and $verbose variables. I’m trying to figure out how to pass them on to other cmdlet’s that get called within the function.

Let’s say I have a cmdlet like this:

function DoStuff() {
   [CmdletBinding()]

   PROCESS {
      new-item Test -type Directory
   }
}

If -debug or -verbose was passed into my function, I want to pass that flag into the new-item cmdlet. What’s the right pattern for doing this?

Answer 1

Perhaps it sounds strange, but there isn’t any easy way for a cmdlet to know its verbose or debug mode. Take a look at the related question:

How does a cmdlet know when it really should call WriteVerbose()?

One not perfect, but practically reasonable, option is to introduce your own cmdlet parameters (for example, $MyVerbose and $MyDebug) and use them in the code explicitly:

function DoStuff {
    [CmdletBinding()]
    param
    (
        # Unfortunately, we cannot use Verbose name with CmdletBinding
        [switch]$MyVerbose
    )

    process {

        if ($MyVerbose) {
            # Do verbose stuff
        }

        # Pass $MyVerbose in the cmdlet explicitly
        New-Item Test -Type Directory -Verbose:$MyVerbose
    }
}

DoStuff -MyVerbose

UPDATE

When we need only a switch (not, say, a verbosity level value) then the approach with $PSBoundParameters is perhaps better than proposed in the first part of this answer (with extra parameters):

function DoStuff {
    [CmdletBinding()]
    param()

    process {
        if ($PSBoundParameters['Verbose']) {
            # Do verbose stuff
        }

        New-Item Test -Type Directory -Verbose:($PSBoundParameters['Verbose'] -eq $true)
    }
}

DoStuff -Verbose

It’s all not perfect anyway. If there are better solutions then I would really like to know them myself.