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System.Management.Automation.SwitchParameter (struct)

System.Management.Automation.SwitchParameter is used for switch parameters in PowerShell.
This type inherits from System.ValueType.
This type can be «abbreviated» with the [switch] type accelerator.

No difference between IsPresent and explicit cast operator in a function

When using a switch parameter, there is no difference between using IsPresent or reliying on the explicit cast operator of a [switch] parameter, both evaluate to either True or False: 
$p1 = new-object System.Management.Automation.SwitchParameter
$p2 = new-object System.Management.Automation.SwitchParameter $false
$p3 = new-object System.Management.Automation.SwitchParameter $true

$p1.IsPresent  # False
$p2.IsPresent  # False
$p3.IsPresent  # True

[bool] $p1     # False
[bool] $p2     # False
[bool] $p3     # True
More or less the same thing as above, but using a «real» [switch] parameter: 
function f {
   param (
     [switch] $p
   )

 # $p.GetType().FullName # -> System.Management.Automation.SwitchParameter
   "{0,-5} {1}" -f $p.IsPresent, [bool] $p

}

f             # False False
f -p          # True  True
f -p:$true    # True  True
f -p:$false   # False False
In order to check if a [switch] parameter was explicitly set when the function was invoked, $psBoundParameters.ContainsKey('p') needs to be used.

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