Creating powershell modules from multiple files, referencing with module

@Ryan I similarly assumed that dot sourcing wasn't the best choice here, but I'm not so sure anymore. I've used the NestedModules approach as well, but have run up against a specific problem. I've asked the question here: PowerShell module, call function in NestedModule from another NestedModule

In summary I find that the PrimaryModule can call any function in any NestedModule. But one NestedModule is not able to call a function in another NestedModule.

Splitting your code out into many logical files is Developer 101 basics. So I'm really surprised there isn't a standard way of handling this.

Any help here much appreciated. Please read the linked question, it gives plenty of detail. Is the consensus that dot sourcing has to be used? Because I'm finding the module manifest way of splitting out the code very limiting.

Since I recently had to do this myself, I am sharing my solution. I have recently started grouping functions in psm1 files. These can be compiled into a single module with a single manifest.

This allows me to have groups of functions that can be packaged with multiple modules.


Function Write-Bar {
  return "Bar"

Function Write-Baz {
    return "Baz"


Function Write-Foo {
    return "Foo"

Function Write-FooBar {
    $foo = Write-Foo
    $bar = Write-Bar
    return ("{0}{1}" -f $foo, $bar)

Function Write-FooBarBaz {
    $foobar = Write-FooBar
    $baz = Write-Baz
    return ("{0}{1}" -f $foobar, $baz)

Which are combined into a single module like this: (formatted for readability)

    -Path .\Write-FooBarBazCombos 
    -NestedModules @('.\FooFunctions\Write-FooFunctions.psm1', '.\BarFunctions\Write-BarFunctions.psm1') 
    -Guid (New-Guid) 
    -ModuleVersion '' 
    -Description 'demonstrate multiple psm1 files as 1 powershell module with 1 powershell module manifest' 
    -PowerShellVersion $PSVersionTable.PSVersion.ToString() 
    -FunctionsToExport @('Write-Foo', 'Write-Bar','Write-FooBar', 'Write-FooBarBaz')

PowerShell output:

PS C:\LWC\scripting-misc\module-manifest-multiple-files-example> New-ModuleManifest -Path .\Write-FooBarBazCombos.psd1
-NestedModules @('.\Write-FooFunctions.psm1', '.\Write-BarFunctions.psm1') -Guid (New-Guid) -ModuleVersion '' -D
escription 'demonstrate multiple psm1 files as 1 powershell module with 1 powershell module manifest' -PowerShellVersio
n $PSVersionTable.PSVersion.ToString() -FunctionsToExport @('Write-Foo', 'Write-Bar','Write-FooBar', 'Write-FooBarBaz')

PS C:\LWC\scripting-misc\module-manifest-multiple-files-example> Import-Module .\Write-FooBarBazCombos.psd1
PS C:\LWC\scripting-misc\module-manifest-multiple-files-example> Get-Command -Module Write-FooBarBazCombos

CommandType     Name                                               Version    Source
-----------     ----                                               -------    ------
Function        Write-Bar                                    Write-FooBarBazCombos
Function        Write-Foo                                    Write-FooBarBazCombos
Function        Write-FooBar                                 Write-FooBarBazCombos
Function        Write-FooBarBaz                              Write-FooBarBazCombos
  • note that Write-Baz is not exposed in the imported module as it is excluded from the FunctionsToExport parameter so Write-FooBarBaz will error (intentional to show behavior).
PS C:\LWC\scripting-misc\module-manifest-multiple-files-example> Write-FooBar

What you're left with in the directory:

PS C:\LWC\scripting-misc\module-manifest-multiple-files-example> Get-ChildItem | Select-Object Name


Addendum - I expanded on this answer in another question - here:

I've personally followed the practice laid out by RamblingCookieMonster in his blog here:

Which is to organise your functions in to separate .ps1 files under sub-folders \Public and \Private. Public contains the functions the user should be able to call directly, Private is for the functions that are only used internally by your module.

Then in the .psm1 file you load the functions via a loop and dot sourcing as follows:

#Get public and private function definition files.
    $Public  = @( Get-ChildItem -Path $PSScriptRoot\Public\*.ps1 -ErrorAction SilentlyContinue )
    $Private = @( Get-ChildItem -Path $PSScriptRoot\Private\*.ps1 -ErrorAction SilentlyContinue )

#Dot source the files
    Foreach($import in @($Public + $Private))
            . $import.fullname
            Write-Error -Message "Failed to import function $($import.fullname): $_"

# Here I might...
    # Read in or create an initial config file and variable
    # Export Public functions ($Public.BaseName) for WIP modules
    # Set variables visible to the module and its functions only

Export-ModuleMember -Function $Public.Basename
  • Source of this example:

You should then also explicitly list your Public function names in your .psd1 module manifest file under the FunctionsToExport setting. Doing this allows these functions to be discoverable and the module to be auto-loaded when they are used.