Question

Here is my code:

function Get-OSInfo {
    param([string]$Computer)
    $OS = gwmi -class Win32_OperatingSystem -computer $Computer
    $OS | Add-Member –MemberType NoteProperty –Name OSType –Value ""
    $OS.OSType = Get-OSType -Input $OS
    write $OS
}

function Get-OSType {
    param([?]$Input)
    if ($Input.ProductType -eq 1) {
        write "Client OS"
    }
}

$blah = Get-OSInfo -Computer mypc
$blah | fl *

I realize that this could be done with a single function (or in the body of the script itself), but I have simplified the functions to highlight the trouble I’m having. What I want to do is pass the gwmi dataset from the Get-OSInfo function as a parameter variable in the Get-OSType so I can reference all of its properties in the second function without passing them individually from the first. Clear as mud?

I have tried multiple parameter accelerator types, [ref], [array], [object[]], etc., but I haven’t found anything that works as a parameter. The only thing that has proven to work is to change the second function to use args[0] for accepting input, but that is not as clean as using parameters, and since it works, I can’t help but think there is a parameter that should work as well.

Answer 1

Avoid using $input as that has special meaning in functions (representing pipeline input). Just rename the parameter to something like $OS.

The docs (man about_automatic_variables) on $input say:

Contains an enumerator that enumerates all input that is
passed to a function. The $input variable is available only to
functions and script blocks (which are unnamed functions). In the
Process block of a function, the $input variable enumerates the
object that is currently in the pipeline. When the Process block
completes, there are no objects left in the pipeline, so the $input
variable enumerates an empty collection. If the function does not
have a Process block, then in the End block, the $input variable
enumerates the collection of all input to the function.