Example of dynamic parameters with PowerShell

test.ps1

function Test {
    [cmdletbinding()]
    param(
        [Parameter(Mandatory=$true,Position=1)]
        [string]$smtpServer,

        [Parameter(Position=2)]
        [switch]$logging,

        [Parameter(Position=4)]
        [switch]$testing

    )
    DynamicParam {
        
        if( $logging -or $testing) {
        
            $paramDictionary = New-Object System.Management.Automation.RuntimeDefinedParameterDictionary
        
        }
        
        if ($logging) {

            $logPathAttribute = New-Object System.Management.Automation.ParameterAttribute -Property @{
                Position = 3
                Mandatory = $true
                HelpMessage = 'Plesae enter path to log.'
            }
            
            $attributeCollection = new-object System.Collections.ObjectModel.Collection[System.Attribute]  
            $attributeCollection.Add($logPathAttribute)
            $logPathParam = New-Object System.Management.Automation.RuntimeDefinedParameter('LogPath', [String], $attributeCollection)
            $paramDictionary.Add('LogPath', $logPathParam)
        
        }

        if ($testing) {
            
            $testRecipientAttribute = New-Object System.Management.Automation.ParameterAttribute -Property @{
                Position = 5
                Mandatory = $true
                HelpMessage = 'Plesae enter recipent.'
            }
            
            $attributeCollection = new-object System.Collections.ObjectModel.Collection[System.Attribute]  
            $attributeCollection.Add($testRecipientAttribute)
            $testRecipientParam = New-Object System.Management.Automation.RuntimeDefinedParameter('TestRecipient', [String], $attributeCollection)
            $paramDictionary.Add('TestRecipient', $testRecipientParam)
        
        }

        if($logging -or $testing) {
       
              return $paramDictionary
 
        }
    }

    Process {
        
        # Actual code goes here

    }
}