Why weird assignment from variable inside Powershell switch statement?

Question

I'm a beginner at Powershell and am struggling to understand some syntax from some code I found on Github. I've read the docs on Powershell assignment, and on switch statements, and can't understand what is going on with the = $Yes and = $No in this code snippet:

Switch ($Prompt3) {
  Yes {
         Stop-EdgePDF
         Write-Output "Edge will no longer take over as the default PDF viewer."; = $Yes
   }
  No   {
         = $No
   }
}

I haven't been able to find any references to this kind of syntax, and it doesn't seem to do anything in the script. So why is it there?

= is being overloaded as a function or alias. There is code missing from your example. Observe: ${function:=} = { $args }; = 'test' or function = { $args } is another syntax — Maximilian Burszley
– Maximilian Burszley, Commented Nov 21, 2018 at 22:58
The issue has been resolved in the latest version of the script. See github.com/Sycnex/Windows10Debloater/issues/66 Voting to close because this was a typographical error. — Bacon Bits
– Bacon Bits, Commented Dec 3, 2018 at 17:11

Bacon Bits · Accepted Answer · 2018-12-03 17:07:51Z

1

UPDATE: This issue has been resolved.

Looks to me like the variable name that was getting the assignment was deleted in a change back in August.

$PublishSettings = $Yes

Was changed to:

= $Yes

And:

$PublishSettings = $No

Was changed to:

= $No

Looks like poor search and replace.

I've created an issue for the problem at GitHub.

edited Dec 3, 2018 at 17:07

answered Nov 27, 2018 at 22:35

Bacon Bits

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Comments

Maximilian Burszley · Accepted Answer · 2018-11-27 19:23:05Z

1

There are many characters that are valid in a function (or variable) name; this includes the = symbol. What you're observing is a function or alias.

Examples:

# standard function
function =
{
    return $args
}

# accessing the function: drive
${Function:=} = {
    return $args
}

# defining a new alias
New-Alias -Name = -Value Get-Variable

# using the Alias attribute
function Test-Thing
{
    [Alias('=')]
    param()

    return $args
}

edited Nov 27, 2018 at 19:23

answered Nov 21, 2018 at 23:10

Maximilian Burszley

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9 Comments

jacobsee Over a year ago

Thank you for your answer. I've read it several times but still having a hard time wrapping my head around it. You're right that I didn't include all the code, but one other detail to mention is that the variables (aliases?) $Yes and $No are not used any where else in the PS script, which includes several Functions followed by several Switches based on user prompts like the one shown.

Maximilian Burszley Over a year ago

@jacobsee I'm assuming there's something that looks like $Yes = switch(condition) { somewhere in the codebase. If the variable is undefined, it returns $null

jacobsee Over a year ago

There is not. But if there were, what would that do? In my example, what is being assigned to the $No variable? It's an empty pair of brackets!? Thanks for your patience.

Maximilian Burszley Over a year ago

@jacobsee That's where your misunderstanding is coming - = is not an assignment operator in your code, it's a function call. Someone has literally defined a function named =. { } is an empty scriptblock being passed to the = function. You can assign expression outputs to variables, such as: $myvar = if ($true) { 'thisval' } else { 'thatval' }

Maximilian Burszley Over a year ago

@jacobsee Yeah, I reviewed the project and there's no definition for a = function or alias so that line of code would throw an exception.

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