Brandon and I have been talking a lot about error handling in #PowerShell (on irc.freenode.net) the last few weeks, going back and forth (and dragging half the other channel participants into the discussion) with examples and counter examples and trying to make sense of how it’s supposed to work, and how it really does work. I’m sure he’s about to write about TRAP from the perspective of a sysadmin, but I thought I’d throw out this post as a complement to his — from the perspective of a programmer.

The biggest problem with error handling in PowerShell is an almost complete lack of documentation. Neither the trap statement or the throw statement even have about_ documents in the powershell help system, nor do they have pages on MSDN (that I can find). In fact, it’s so bad that I’ve been known on the IRC channel to accuse the PowerShell developers of deliberately not writing documentation so that they and the various MVPs could make some extra cash selling books about PowerShell. Despite that, we’ve been able by trial and error to deduce how these things work, and hopefully this explanation will help some of you come to a better understanding of how you can use error handling in PowerShell. (more…)