In PowerShell, you can write-protect functions. When you do, a function cannot be changed, overwritten or removed anymore during a running PowerShell session. While there may be no apparent use case for this, here is the technique:
$code = { param ( [string] [Parameter(Mandatory)] $SomeParameter ) "I have received $SomeParameter and could now process it..." } $null = New-Item -Path function:Invoke-Something -Options Constant,AllScope -Value $code # run the function like this Invoke-Something -SomeParameter "My Data"
Since the function is constant now, trying to redefine it will fail:
# you can no longer overwrite the function # the following code raises an exception now function Invoke-Something { # some new code }
The only way to get rid of the function is to restart your PowerShell session. A more useful scenario may be constant variables: by storing important data in write-protected variables, you can ensure that they cannot be changed by accident or on purpose. This line defines a write-protected variable $testserver1 with some content:
Set-Variable -Name testserver1 -Value server1 -Option Constant, AllScope
