Out-String should not append a trailing newline

Summary of the new feature/enhancement

It should be possible to use Out-String in a manner that doesn’t append a trailing newline, which is what it currently does and has always done.

Note that -NoNewLine is not a solution, because it suppresses all newlines, so that two or more output lines are then simply directly concatenated (like -join ''; e.g. 1, 2 | Out-String -NoNewLine yields 12).

Here’s a demonstration of the problem:

# CURRENT behavior:
PS> ('foo' | Out-String) -replace '\r?\n', '<newline>'
foo<newline>   #  A newline was appended.

I see two options:

• (a) Consider a breaking change - assuming it is justified to consider it a Bucket 3: Unlikely Grey Area change - and make Out-String never append a trailing newline.

• (b) Introduce a new switch, -NoTrailingNewLine (related: #5108)

[bpayette]

there’s no good reason to append a newline to the (formatted representation) of the last input object.

The purpose of Out-String is to render objects as presentable text which includes trailing newlines. If what you actually want to do is join a bunch of strings then use -join because that’s it for.

[jazzdelightsme]

I think maybe mklement0 chose Get-Date as an example because it produces a simple object that isn’t a string (a DateTime), so that Out-String would be doing “some work” to convert something to a string.

But consider even just a plain string!

'asdf'

versus

'asdf' | Out-String

How would one could consider that 'asdf' is not “rendered as presentable text”? In other words, who would consider the output of the latter to be “presentable text”, but not the former?

Adding newlines in is ONLY interesting where there are multiple input objects: newlines in that case are used to separate them (unless belayed by -NoNewline). The current last (trailing) newline is separating the last object from … what? It serves no purpose; it is not separating it from anything. We should get rid of it.

Consider also this pathological scenario:

'asdf' | Out-String | Out-String | Out-String | Out-String | Out-String 

Let’s stop the madness and pull this burr out from under the saddle.

(edit: I called that last scenario “pathological”, because nobody is going to pipe through a long chain of Out-String commands, but I think the nerve it hits is quite reasonable: it feels like it ought to be idempotent)