AvoidDefaultValueSwitchParameter

Severity Level: Warning

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.

Don't define a switch parameter with a default value of $true because a switch parameter is already $false when it isn't specified. Leave the switch parameter without a default value so it behaves as designed.

How

To fix this issue, don't assign a default value of $true to a [switch] parameter. Declare the switch without a default value and write your logic so the parameter is treated as $false when the caller doesn't supply it.

More information

See Strongly Encouraged Development Guidelines.

Example

Noncompliant

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

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

Preferred

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

        [switch]
        $Switch
    )
    ...
}