Function Args

I was trying to make a quick and dirty process killer and I ran across
something I don't understand. Here is a function that will do what I expect
it to:
function showit
{
$Args[0]
}
When you call the function with a parameter, the paramter is displayed:
14:55:09 C:\> showit foo
foo

This is a function that works
function showNotepad
{
get-process | where{$_.ProcessName -eq "notepad"}
}
It will display the data on the notepad process if you have notepad open:
14:59:28 C:\> showNotepad

Handles NPM(K) PM(K) WS(K) VS(M) CPU(s) Id ProcessName
------- ------ ----- ----- ----- ------ --
-----------
47 2 1012 3404 30 0.09 5068
notepad

This function does not work:
function doNotShow
{
get-process | where{$_.ProcessName -eq $Args[0]}
}
If you run it looking for notepad you get nothing back:
15:03:56 C:\> doNotShow notepad
15:04:01 C:\>

And then lastly, this does work:
function showProcess
{
param([string]$proc)
get-process | where{$_.ProcessName -eq $proc}
}
You get the info on running processes named whatever you pass to it:
15:09:05 C:\> showProcess notepad

Handles NPM(K) PM(K) WS(K) VS(M) CPU(s) Id ProcessName
------- ------ ----- ----- ----- ------ --
-----------
47 2 1036 3428 30 0.19 4320
notepad
47 2 1012 3408 30 0.09 5068
notepad


Now I suspect this behavior has to do with the explicit cast that the param
does, but I was looking for some confirmation just to better help me
understand.

 

This works:

MSH> function dontShow { $n = $args[0]; "name is $n"; get-process | where {
$_.ProcessName -ne $n}}

I wonder if you have found a bug. I've noticed that processing things like
$args[0] and the value of that is say "foo" can sometimes results in
$args[0] evaluating to "foo[0]".

 

The $args[0] in function foo {gps | where {$_.name -eq $args[0]}} is args to
the script block {$_.name -eq $args[0]}. In this case, $args[0] will be
$null. Since there isn't a process on the machine whose name is null, you
don't get any return.

You could try function foo {$firstArg = $args[0]; gps | where{$_.name -eq
$firstArg}}.

 

Ahh! The light goes on. Is that new for beta 3?

 

I don't think so. That $args[0] refers to the script block in function foo
defined in my previous posting has been the behavior prior to Beta 3.

--
Kevin Loo [MSFT]
Microsoft Command Shell Development
Microsoft Corporation
This posting is provided "AS IS" with no warranties, and confers no rights.

 

When put that way it does make sense. Thank you for clearing it up.