Powershell: How to properly implement mode switch in parameters? - powershell

Question

I have a code in my function that works well for me, was inspired by another SO answer, but is marked as improper in VSCode. I would like to improve on it, but currently I have no idea how.
Param(
[Parameter( Mandatory = $True,
ValueFromPipelineByPropertyName = $true,
Position = 0,
ParameterSetName = "Info")]
[switch] $Info = $false,
[Parameter( Mandatory = $True,
ValueFromPipelineByPropertyName = $true,
Position = 0,
ParameterSetName = "Warn")]
[switch] $Warn = $false,
[Parameter( Mandatory = $True,
ValueFromPipelineByPropertyName = $true,
Position = 0,
ParameterSetName = "Error")]
[switch] $Error = $false,
[Parameter( Mandatory = $True,
ValueFromPipelineByPropertyName = $true,
Position = 0,
ParameterSetName = "Fatal")]
[switch] $Fatal = $false,
[Parameter( Mandatory = $True,
ValueFromPipelineByPropertyName = $true,
Position = 0,
ParameterSetName = "Debug")]
[switch] $Debugging = $false,
)
switch ($PSBoundParameters.Keys) {
'Info' { $level = "INFO"
$color = "Green" }
'Warn' { $level = "WARNING"
$color = "Yellow" }
'Error' { $level = "ERROR"
$color = "Red" }
'Fatal' { $level = "FATAL"
$color = "DarkRed" }
'Debugging' { $level = "DEBUG"
$color = "Magenta" }
}
The error is https://github.com/PowerShell/PSScriptAnalyzer/blob/master/RuleDocumentation/AvoidDefaultValueForMandatoryParameter.md - I get that, but how to transform this code so that it is kosher and still performs the same function?

Answer 1

PSSA complains because the Mandatory flag applies to the user - the user must specify arguments for all parameters marked Mandatory in a parameter set - and since the user is already required to supply arguments, it makes no sense to default values, PowerShell will never use them.
The local variables corresponding to the switch parameters in the parameter sets NOT chosen will default to a $null-like value, equivalent to $false anyway:
Param(
[Parameter( Mandatory = $True,
ValueFromPipelineByPropertyName = $true,
Position = 0,
ParameterSetName = "Info")]
[switch] $Info,
[Parameter( Mandatory = $True,
ValueFromPipelineByPropertyName = $true,
Position = 0,
ParameterSetName = "Warn")]
[switch] $Warn,
[Parameter( Mandatory = $True,
ValueFromPipelineByPropertyName = $true,
Position = 0,
ParameterSetName = "Error")]
[switch] $Error,
[Parameter( Mandatory = $True,
ValueFromPipelineByPropertyName = $true,
Position = 0,
ParameterSetName = "Fatal")]
[switch] $Fatal,
[Parameter( Mandatory = $True,
ValueFromPipelineByPropertyName = $true,
Position = 0,
ParameterSetName = "Debug")]
[switch] $Debugging,
)