Switch statement not processing

Question

I'm attempting to use a switch statement to control flow in my PowerShell script, but the switch isn't being processed at all. If I run it interactively (highlight + F8 in ISE), it works without a hitch. I validate the argument, and have tested it thoroughly. If(){} statements process properly. Is there some kind of weird bug with switch statements? Even the Default argument isn't being triggered.

[CmdletBinding()]
Param(
    [Parameter(Mandatory=$True)]
    [ValidateSet('Install','Uninstall','Verify','Enable','Disable')]
    [String]$Switch
)

**FUNCTIONS**

[Int]$R = 324
Start-Transcript 'Path\ESD.log' -Append -Force

Switch ($Switch)
{
    "VERIFY"    { $R = Verify;    Break }
    "INSTALL"   { $R = Install;   Break }
    "UNINSTALL" { $R = Uninstall; Break }
    "ENABLE"    { $R = Enable;    Break }
    "DISABLE"   { $R = Disable;   Break }
    Default { Write-Host "Unable to match: $Switch" -BackgroundColor Red }
}

Write-Host "Exiting with: $R"
Stop-Transcript
EXIT $R

Output:

PS Path\EnterpriseSiteDiscovery> .\ESD verify
Transcript started, output file is Path\ESD.log
Exiting with: 324
Transcript stopped, output file is Path\ESD.log

PS Path\EnterpriseSiteDiscovery> $LASTEXITCODE
324

Content of log:

**********************
Windows PowerShell transcript start
Start time: 20170705154435
**SYSTEMINFO**
**********************
Transcript started, output file is Path\ESD.log
Exiting with: 324
**********************
Windows PowerShell transcript end
End time: 20170705154436
**********************

That code can't work because the $R assignments in the switch block are assigning unquoted strings (unless those are function names, in which case you should "stub in" function outputs for testing purposes). In other words: Update your code to improve your SSCCE. — Bill_Stewart
– Bill_Stewart, Commented Jul 5, 2017 at 20:12
@Bill_Stewart The entire switch statement isn't getting processed at all. If I comment out the conditions and only have Default in there, still nothing. — Maximilian Burszley
– Maximilian Burszley, Commented Jul 5, 2017 at 20:17
Interesting question that was difficult to google, but $switch as a name seemed suspicious :) — Mark Wragg
– Mark Wragg, Commented Jul 5, 2017 at 20:27

Mark Wragg · Accepted Answer · 2017-07-05 20:25:08Z

2

It turns out when you are inside a Switch construct, the variable $Switch value is redefined (presumably by the switch construct itself) as an empty variable of type System.Collections.IEnumerator. The value is set to $null. This won’t be a problem if you’re not using a variable with the name $Switch. Unfortunately I was because I was working with a set to Virtual Switches so $Switch seemed like a fair choice of variable name.

https://dscottraynsford.wordpress.com/2015/09/08/powershell-dont-of-the-week-switch-in-a-swtich/

answered Jul 5, 2017 at 20:25

Mark Wragg

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