Recursive -Verbose in Powershell

Question

Is there an easy way to make the -Verbose switch "passthrough" to other function calls in Powershell?

I know I can probably search $PSBoundParameters for the flag and do an if statement:

[CmdletBinding()]
Function Invoke-CustomCommandA {
    Write-Verbose "Invoking Custom Command A..."

    if ($PSBoundParameters.ContainsKey("Verbose")) {
        Invoke-CustomCommandB -Verbose
    } else {
        Invoke-CustomCommandB
    }
}

Invoke-CustomCommandA -Verbose

It seems rather messy and redundant to do it this way however... Thoughts?

Answer 1

One way is to use $PSDefaultParameters at the top of your advanced function:

$PSDefaultParameterValues = @{"*:Verbose"=($VerbosePreference -eq 'Continue')}

Then every command you invoke with a -Verbose parameter will have it set depending on whether or not you used -Verbose when you invoked your advanced function.

If you have just a few commands the do this:

$verbose = [bool]$PSBoundParameters["Verbose"]
Invoke-CustomCommandB -Verbose:$verbose

Answer 2

I began using KeithHill's $PSDefaultParameterValues technique in some powershell modules. I ran into some pretty surprising behavior which I'm pretty sure resulted from the effect of scope and $PSDefaultParameterValues being a sort-of global variable. I ended up writing a cmdlet called Get-CommonParameters (alias gcp) and using splat parameters to achieve explicit and terse cascading of -Verbose (and the other common parameters). Here is an example of how that looks:

function f1 {
    [CmdletBinding()]
    param()
    process
    {
        $cp = &(gcp)
        f2 @cp
        # ... some other code ...
        f2 @cp
    }
}
function f2 {
    [CmdletBinding()]
    param()
    process
    {
        Write-Verbose 'This gets output to the Verbose stream.'
    }
}
f1 -Verbose

The source for cmdlet Get-CommonParameters (alias gcp) is in this github repository.

Answer 3

How about:

$vb = $PSBoundParameters.ContainsKey('Verbose')
Invoke-CustomCommandB -Verbose:$vb