Indentation for lines after a pipe character

[JohnLBevan]

When we have multiple commands, each piping their output to one another, for readability / single-line width it's generally best to put each command on a different line; like so:

Write-Verbose 'Before the stuff in the piped code'
$myArrayOfThings |
 Where-Object {$_.SomeText -like 'pattern*'} |
 ForEach-Object {[PSCustomObject]@{
 MyText = $_.SomeText -replace '^pattern', ''
 AnotherProperty = $_.SomethingElse
 }}
Write-Verbose 'No longer in the piped code'

Should we define a best practice / guideline for this scenario?

Generally I indent all lines after the initial pipe to show they're a continuation of the previous line. However I don't indent again after subsequent lines because there would be no additional benefit.

The downside with this approach is that there's no "closing line"; which looks nasty if you the following line is a close for a parent block; e.g.

if ($someFlag) {
 $myArrayOfThings |
 Where-Object {$_.SomeText -like 'pattern*'} |
 ForEach-Object {[PSCustomObject]@{
 MyText = $_.SomeText -replace '^pattern', ''
 AnotherProperty = $_.SomethingElse
 }}
} # here we 're now have 8 spaces between this line's indentation level and the preceding line's.

An option to tidy this up could be to put a comment to represent the close of he piped "block" / maybe with something after the comment character to show it's a close for the piped input; e.g.

if ($someFlag) {
 $myArrayOfThings |
 Where-Object {$_.SomeText -like 'pattern*'} |
 ForEach-Object {[PSCustomObject]@{
 MyText = $_.SomeText -replace '^pattern', ''
 AnotherProperty = $_.SomethingElse
 }}
 # |
}

Another option could be to put parentheses around the block.

if ($someFlag) {
 ($myArrayOfThings |
 Where-Object {$_.SomeText -like 'pattern*'} |
 ForEach-Object {[PSCustomObject]@{
 MyText = $_.SomeText -replace '^pattern', ''
 AnotherProperty = $_.SomethingElse
 }}
 )
}

Do others have any thoughts or preferences on how best to approach these scenarios?

[Jaykul]

That's definitely how I prefer to see it handled:

• Wrap on pipe (if the line's long enough to wrap)
• Indent if you wrap on pipeline.

I guess I'm used to Python and Yaml, but I do not worry about the lack of the closing line.

I would not use parenthesis to try and show the end of a block, if only because they have side effects. This, for example, would result in outputting $Moved.

($Moved = Get-ChildItem $SourceFolder |
 Where Length -gt 100mb |
 Move-Item -Destination $TargetFolder -Passthru
)

[JohnLBevan]

Thanks @Jaykul

Agreed; an assignment within brackets has side effects / for that (if adopting the brackets approach) I'd place the bracket after the equals sign:

$Moved = (
 Get-ChildItem $SourceFolder |
 Where Length -gt 100mb |
 Move-Item -Destination $TargetFolder -Passthru
)

... but you're right that the approach of using brackets may lead to people placing the bracket before the assignment and being caught out.

[Jaykul]

But it's more than that. Parentheses are also blocking. Compare:

1..100 | 
 ForEach { start-sleep -m 100; $_ }

(1..100 | 
 ForEach { start-sleep -m 100; $_ }
)