Encapsulating Powershell Functions - function

Question

I am at a lost as to how to perform the following task. As with class members in OOP, we are allowed to hide away implementation with a private modifier. My goal is to create a base powershell function that contains logic that is used by several functions for code reuse while hiding away that function from global access. According to the following reference https://ss64.com/ps/syntax-scopes.html , the following scopes are available Global, Script, and Private. My labeling of the functions do not produce the desired result. The ecapsulated function should work as shown below.
function Invoke-VMDoSomething {
Invoke-PrivateMiniFunc
}
function Invoke-VMDoSomethingElse {
Invoke-PrivateMiniFunc
}
function Invoke-PrivateMiniFunc {
###BaseReuseable code
}
Hypothetical Command Prompt
PS > Invoke-VMDoSomething <<<Invoke-PrivateMiniFunc Executes successfully
PS > Invoke-VMDoSomethingElse <<<Invoke-PrivateMiniFunc Executes successfully
PS > Invoke-PrivateMiniFunc <<<Fails Cannot find Such Commandlet -- Desired result.
How can I implement this convention and do I need to store the functions in a .psm1 file vice a ps1 file? Is it even possible?

Answer 1

Maybe not exactly what you are after, but you can hide functions inside a module.
In your case, create a new file and save it as *.psm1 (for demo I call it InvokeModule.psm1)
function Invoke-VMDoSomething {
Invoke-PrivateMiniFunc
}
function Invoke-VMDoSomethingElse {
Invoke-PrivateMiniFunc
}
function Invoke-PrivateMiniFunc {
Write-Host "Called by: $((Get-PSCallStack)[1].FunctionName)"
}
# export the functions you want to make available and leave out
# the functions you want to keep hidden (but available to the functions in the module)
Export-ModuleMember -Function Invoke-VMDoSomething, Invoke-VMDoSomethingElse
The last command Export-ModuleMember defines what functions you want exposed en what not.
Next, in another file import that module.
In there, only the Exported functions are visible/callable but the Invoke-PrivateMiniFunc is not:
Import-Module 'D:\InvokeModule.psm1'
Invoke-VMDoSomething # works as expected
Invoke-VMDoSomethingElse # works as expected
Invoke-PrivateMiniFunc # errors out
Result:
Called by: Invoke-VMDoSomething
Called by: Invoke-VMDoSomethingElse
Invoke-PrivateMiniFunc : The term 'Invoke-PrivateMiniFunc' is not recognized as the name of a cmdlet,
function, script file, or operable program. Check the spelling of the name, or if a path was included,
verify that the path is correct and try again.
At line:7 char:1
+ Invoke-PrivateMiniFunc
+ ~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (Invoke-PrivateMiniFunc:String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException