Displaying SwitchParameter causes subsequent output to fail...

Put this in a file like testme.ps1:

param(
  [switch]$skip = $false,
  [switch]$weird = $false
)

if (! $skip) {
    $weird  # skip this line and it works!
}

$hash2=@{}

$hash2["aaa"]=1

"hash value is"

$hash2

Without the -skip parameter, nothing gets printed for the hash value…

PS C:\temp> powershell .\testme.ps1

IsPresent
---------
    False
hash value is

PS C:\temp> powershell .\testme.ps1 -skip
hash value is

Name                           Value
----                           -----
aaa                            1

PS C:\temp>

I would have expected the hash value output to be the same in both cases?

I see the same behavior on Core 7.1.3 and Desktop 5.1.19041.906.

Is there a workaround?

Thanks.

[vexx32]

Yeah, I’d echo @jhoneill’s point and say if you need informational / debugging messages, use of Write-Verbose / Write-Debug and/or Write-Host depending on your exact needs is what you really want; those all avoid putting the data in the output stream and causing issues like this.

For errors I’d use throw or Write-Error, or (specifically in a function with [cmdletbinding()]) you can also use $PSCmdlet.ThrowTerminatingError() or $PSCmdlet.WriteError().

That is a bit tangential; this behaviour is still broken, but hopefully using those you should be able to work around it for the current problem you have. 🙂

[jhoneill]

I tend to recommend against having more than one type of object be output from a single function

I think I agree – but when you get errors and such and/or start trying to instrument code to see what is going on, that becomes pretty hard to ensure.

It is at this point write-verbose and write-debug become your friends

[cmdletbinding()]
param(
  [switch]$skip ,
  [switch]$weird 
)
if (! $skip) {
    Write-Verbose     $weird  
}
$hash2=@{}
$hash2["aaa"]=1
"hash value is"
$hash2
}

As @vexx32 said

[it] is still output. If you do $data = & ./testme.ps1 then $data will still have all three values in it.

Unless you use verbose/debug/host the instrumentation gets mixed up with the output and you need need to keep enabling and disabling it.

(the behavior after outputting a switch is still broken, but that’s another issue)