How to Access Custom PowerShell 5.0 Classes from a separate ps1 file

Question

I created a class in a ps1 file that works just fine IN the ps1 file itself. I can run various tests with the class and the tests in the same file.

My trouble is I don't seem to be able to find a way to put my Class in one file and the Class Usage code in another.

With functions, you can just dot source them to bring any external ps1 files into your current script. It looks like Classes for Powershell do not work this way.

How can I organize code to keep classes in separate files from the executing script?

Do I have to use modules? How do I do that?

Just create a module and use the using directive: https://stackoverflow.com/questions/31051103/how-to-export-a-class-in-powershell-v5-module — Jean-Claude Colette, Jan 01 '18 at 16:57
Can you elaborate and possibly offer a simple example of what the content of both files would look like? I have read the reference you sent already.. read it many times and tested every example on that link... NONE of them work consistently. — user5855178, Jan 01 '18 at 17:20
I guess I should elaborate. By not working consistently I mean I have to shut down the console window/Powershell editor in order for any file changes to actually take. It looks like MS caches these modules someplace, so when you re-run them, your delta gets ignored/overlooked. The using statement does help, but it's not enough. — user5855178, Jan 01 '18 at 22:17
The fact that "using module" does not reload is a known shortcoming. I recommend you upvote this issue on Github for getting it fixed in PSCore: https://github.com/PowerShell/PowerShell/issues/7654 — Dave_J, Oct 24 '18 at 08:26

score 3 · Answer 1 · answered Jan 02 '18 at 10:53

In the file Hello.psm1:

class Hello {
# properties
[string]$person

# Default constructor
Hello(){}

# Constructor
Hello(
[string]$m
){
$this.person=$m
}

# method
[string]Greetings(){
return "Hello {0}" -f $this.person
}

}

In the file main.ps1:

using module .\Hello.psm1

$h = New-Object -TypeName Hello
echo $h.Greetings()
#$hh = [Hello]::new("John")
$hh = New-Object -TypeName Hello -ArgumentList @("Mickey")
echo $hh.Greetings()

And running .\main.ps1:

Hello 
Hello Mickey

score 1 · Answer 2 · answered Jan 03 '18 at 00:21

This may not apply to your case, but I have had nightmares with PowerShell caching information (in my case it was just for modules). Things I'd changed in the module weren't being properly loaded - even after a reboot.

I found deleting the cache stored in a subdirectory of C:\Users\<YourUsername>\AppData\Local\Microsoft\Windows\PowerShell solved my issue.

score 0 · Answer 3 · answered Sep 21 '22 at 12:05

The simplest solution is to use the using keyword, at the very beginning of your script :

using module .\path\to\your\Module.psm1

Path can be relative from your current file.

To prevent caching problem, use powershell.exe .\script.ps1 to execute it, even in the PoweShell ISE console.

How to Access Custom PowerShell 5.0 Classes from a separate ps1 file

3 Answers3