Powershell: How to pipeline array itself instead of its items - powershell

Question

How to write function which get array as object from pipeline (actually any object) without to iterate over its items and another one argument (positional). Goal is to modify container (array), but not their items. Something like:
function xxx {
Param( magic-specification??? )
if ($obj type is array) {
iterate over $obj items {
$res = executes $args[0] script-block over them ($_)
if ($res) modify $obj
}
else if ($obj type is object) {
iterate over $obj properties {
$res = executes $args[0] script-block over them ($_)
if ($res) modify $obj property
}
}

Answer 1

here's a demo of how to bypass the way that PoSh is intended to unroll items sent across the pipeline ...
,#(1,2,3) | ForEach-Object {$_.GetType(); "$_" } | Out-Host
#(1,2,3) | ForEach-Object {$_.GetType(); "$_" } | Out-Host
1,2,3 | ForEach-Object {$_.GetType(); "$_" } | Out-Host
output ...
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Object[] System.Array
1 2 3
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Int32 System.ValueType
1
True True Int32 System.ValueType
2
True True Int32 System.ValueType
3
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Int32 System.ValueType
1
True True Int32 System.ValueType
2
True True Int32 System.ValueType
3
note that the 1st one has passed thru an array while the others all unrolled the array. that leading , is the array operator and it causes PoSh to send the array wrapped in another array. the outer one gets unrolled, the inner one gets passed on as an array.