> because I didnt read the docs

Ouch.

> Or is it a separate routine that you have to write?

If you are writing a function or a module what would do something (eg API wrapper) then of course you need to write it yourself.

But if you are writing just a script for your mundade one-time/everyday tasks and call cmdlets what supports ShouldProcess then it works automagically. Issuing '-whatif' for the script would pass `-whatif` to any cmdlet what has 'ShouldProcess' in it's definition. Of course if someone made a cmdlet with a declared ShouldProcess but didn't write the logic to process it - you are out of luck.

But if have a spare couple of minutes check the docs in the link, it was originally a blog post by kevmarq, not a boring autodoc.