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powershell/PSAvoidDefaultValueSwitchParameter is a PSScriptAnalyzer diagnostic emitted by tally for PowerShell snippets embedded in Dockerfiles.
PropertyValue
SeverityWarning
CategoryPSScriptAnalyzer
Auto-fixNo

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Description

If your parameter takes only true and false, define the parameter as type [Switch]. PowerShell treats a switch parameter as true when it’s used with a command. If the parameter isn’t included with the command, PowerShell considers the parameter to be false. Don’t define [Boolean] parameters. You shouldn’t define a switch parameter with a default value of $true because this isn’t the expected behavior of a switch parameter.

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How

Change the default value of the switch parameter to be $false or don’t provide a default value. Write the logic of the script to assume that the switch parameter default value is $false or not provided.

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Examples

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Problematic code

function Test-Script
{
    [CmdletBinding()]
    Param
    (
        [String]
        $Param1,

        [switch]
        $Switch=$True
    )
    ...
}

​
Correct code

function Test-Script
{
    [CmdletBinding()]
    Param
    (
        [String]
        $Param1,

        [switch]
        $Switch
    )

    begin {
        # Ensure that the $Switch is set to false if not provided
        if (-not $PSBoundParameters.ContainsKey('Switch')) {
            $Switch = $false
        }
    }
    ...
}

​
More information

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Source

This rule documentation is adapted from Microsoft’s PSScriptAnalyzer documentation for AvoidDefaultValueSwitchParameter, licensed under CC BY 4.0.