As for the specific problem I mentioned: I worked around it as follows (and there may well be a better v2 solution to this, I just haven’t studied what’s new in v2 yet); the side effect is that all pipeline input is collected before it gets passed to the underyling cmdlet:

# In the ‘begin’ block, declare a variable to
# collect all pipeline input
$allPipeInput = New-Object Collections.ArrayList

# In the ‘process’ block, if $_ is non-null,
# collect pipeline items.
[void] $allPipeInput.Add($_)

# Finally, in the ‘end’ block, if $allPipeInput
# is non-empty, make it part of the command line.
Invoke-Expression “`$(`$allPipeInput.GetEnumerator()) | …”

A note on Invoke-Cmdlet:

It won’t work as expected with cmdlets that operate on the pipeline *as a whole*, e.g. Get-Member, given that it invokes the underlying cmdlet for each object in the pipeline.

I think you are correct about tabexpansion and get-command extending ( PowerTab is using get-Command and hence only provides the parameter when in the provider it works on .

but I will take a look also at adding this functionalty into PowerTab using the get-help option, as this might be not always wanted (triggering only when valid as in you last example will be hard to do )
.

Greetings /\/\o\/\/