Scripting Games 2012 comments: #19 default parameters

I often saw scripts that did something like this

function test1 {            
 param (            
   [string]$computername            
 )            
            
if (!$computername){            
  $computername = $env:COMPUTERNAME            
}            
            
Get-WmiObject -Class Win32_OperatingSystem -ComputerName $computername              
}

A function, or script, defines a parameter. The first thing the function does it test the value of the parameter and if it doesn’t exist it sets it to a default value.

No, no, no – you are making work for yourself. 

Get PowerShell to do the work for you

function test2 {            
 param (            
   [string]$computername = $env:COMPUTERNAME            
 )            
            
Get-WmiObject -Class Win32_OperatingSystem -ComputerName $computername              
}

See the difference?

The parameter definition now contains a default value.  If you don’t specify the parameter and a value the default kicks in and the function works.

Cuts down typing and gets PowerShell to do the work.