Vista - credential in the pipeline

I'm writing a cmdlet that can take a PSCredential object from the pipeline
(if needed). This cmdlet does some processing and writes an XmlDocument to
the pipeline. A second cmdlet processes this XmlDocument as a parameter or
from the pipeline. It can also take a PSCredential object from the pipeline
if needed.

I would like it to work like this:

get-myxml | update-myxml

and

get-credential me | get-myxml | update-myxml

(note that I just want the user to provide the credential once, not once for
each cmdlet in the pipeline)

I've been able to pass both a PSCredential and a XmlDocument object in the
pipeline at the same time by adding them both to a PSObject and writting that
to the pipeline. Is this the best way to do this?

I think a side effect of this implementation is that my "by parameter"
interface needs to take a PSObject in order to handle get-myxml output :

$xml = get-myxml
update-myxml $xml

The pipeline interface is able to take "ValueFromPipelineByPropertyName" but
the parameter interface doesn't have this option.

Am I on the right track here? Any suggestions on how to handle the PSObject
as a parameter input? Do I need to switch on type? Thanks in advance...

I think by doing it that way you're straying from the more common approach
of storing credential in a variable and passing it as a parameter. It's also
not entirely intuitive to have different objects flowing along the same
pipeline. While some gurus here might be able to help you work out why it
isn't working, it might be worth at least considering if it's the best way.
To me this seems cleaner:

$c = get-credential me
get-myxml -cred $c | update-myxml -cred $c

and if you're using ps 2.0 you can do something like:

$xargs = @{credential=(get-credential me)}
get-myxml @xargs | update-myxml @xargs

finally, to get way off topic, my favorite approach would be a separate
cmdlet altogether:

update-myxml -cred $c -process {
# in this scriptblock $_ has what get-myxml would retrieve
# modify it as needed and at the end it will update
# effectively combining the two cmdlets from before with
# some scriptblock "glue" in the middle
$_.blah = 'new value'
}

Josh

"MarkTimperley" <MarkTimperley@xxxxxx> wrote in message
newsFF7EE84-65D1-4224-BA63-2531DDC9B40A@xxxxxx

The approach you recommend is certainly easier to implement and if it is what
a PowerShell user would normally expect and/or if the use as I outlined is
beyond what the designers of the pipeline intended it for, then I'll go with
your suggestion.

It seems to me that a pipeline that could pass multiple objects between all
cmdlets connected together would be a useful thing.

I would argue that:

get-credential me | get-myxml | update-myxml

is more elegant than:

$c = get-credential me
get-myxml -cred $c | update-myxml -cred $c

but if the former is not common or expected then any perceived elegance on
my part is not worth the effort (since no one will know to use it).

BTW, your "update-myxml -cred $c -process {..." suggestion has me interested
but I can't say I really understand it yet.

"Josh Einstein" wrote: