CODEWITHSUNDEEP
powershell
KallDrexx
KallDrexx

Reputation: 27813

How can I have a powershell module that sets default parameter values for function calls both in and out of the

In my powershell module I have a function DoStuff that takes parameter foo. When you call the Initialize function I want it to make all invocations of DoStuff pass in a default value for foo if not specified.

Normally, this is done via $PSDefaultParameterValues however I have noticed functions run inside the modules and functions run outside the module (i.e. run from the shell) do not use the same default parameter dictionary.

An example is the following:

function Test1 ([Parameter(Mandatory=$true)][String]$testParam)
{
   $global:PSDefaultParameterValues["Print:output"] = $testParam
}

function Test2 ([Parameter(Mandatory=$true)][String]$testParam)
{
   $PSDefaultParameterValues["Print:output"] = $testParam
}

function CallPrint
{
   Print
}

function Print([Parameter(Mandatory=$true)][String]$output)
{
    Write-Host $output
}

To illustrate my issue I ran the following commands:

PS C:\Users\ms> Import-Module '.\Documents\Test Powershell Scripts\ModuleTest.psm1'

PS C:\Users\ms>Test1 abc

PS C:\Users\ms> Test2 def

PS C:\Users\ms> CallPrint

def

PS C:\Users\ms> Print

abc

What this shows is that $PSDefaultParameterValues is used when calling a function from within the module, but $global:PSDefaultParameterValues is used when calling a function from outside the module.

Is there any way to get consistent behavior without setting both of these at the same time?

Upvotes: 0

Views: 1471

Answers (1)

mjolinor
mjolinor

Reputation: 68303

Since the Global scope and the module scope obviously have their on $PSDefaultParameterValues, you'll have to set both. You can simplify it by setting the global scope first, and then 

$PSDefaultParameterValues = $Global:PSDefaultParameters.clone()

in the module to sync the values.

That being said, setting those values in the global scope sounds like a bad idea with a potential for unintended consequences.

Upvotes: 3

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