How to pass dynamic parameters in Powershell?

Question

I want to call an existing commandlet with a dynamic number of parameters.

So instead of doing this (taking write-host as an example), I would like to do it the smart way.

# these are the dynamic parameters which maybe get passed into my function or script
# they would be $null be default of course
$forecolor = 'Green'
$newline = $true

# now build the "dynamic" write-host...
if ($forecolor) {
    if ($newline) {
        write-host -fore $forecolor "Hello world"
    }
    else {
        write-host -fore $forecolor "Hello world" -nonewline
    }
}
else {
    if ($newline) {
        write-host "Hello world"
    }
    else {
        write-host "Hello world" -nonewline
    }
}

This of course is very ugly. Help me make it prettier!

I already tried just setting $forecolor = '-fore Green' which only outputs "-fore Green Hello world". I could think of passing a list of arguments to a function and for each argument in the list add the according parameter - I just don't know how to hold the parameters.

Answer 1

You can just pass your variables as arguments to Write-Host:

Write-Host -Fore $forecolor -NoNewLine:(!$newline) 'Hello World'

For a truly dynamic way you can use a hashtable:

$params = @{ NoNewLine = $true; ForegroundColor = 'Green' }

and then use the splat operator

Write-Host @params Hello World

You can add parameters and their values to the hashtable as you like before calling Write-Host that way.