Custom Class in a script?-CodePudding

Haven't coded in PowerShell in a few years and have a need to create a custom class. Poked through the docs and a few blogs and custom classes seemed simple enough, but I get the following error whenever I try to load even a simple class from a script.

I've tried running a test script and dot sourcing the file with the class:

The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)
At C:\Temp\test.ps1:1 char:1
  . ./classtest.ps1
  ~~~~~~~~~~~~~~~~~
  CategoryInfo          : OperationStopped: (:) [], FileLoadException
  FullyQualifiedErrorId : System.IO.FileLoadException

Calling the file with the class directly throws the same error:

The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)
At line:1 char:1
  .\classtest.ps1
  ~~~~~~~~~~~~~~~
  CategoryInfo          : OperationStopped: (:) [], FileLoadException
  FullyQualifiedErrorId : System.IO.FileLoadException

I scrapped my entire class and just grabbed a super simple example online as follows(this is what's currently in classtest.ps1 in the above errors):

class student {
    [string]$FirstName
    [string]$LastName
}

If I paste that class into a running PowerShell window, it works just fine. If I put it in a file and try to run it I get the same errors above whether calling the file directly or attempting to dot source the file into another script.

There's got to be something stupidly simple that I am missing here, how does one use a class in a PowerShell script?

CodePudding user response：

Figured it out. Apparently custom class libraries are touchy in PowerShell. Had to save it off to just standard text file, then load that file with Invoke-Expression to load it into my PowerShell script. After that I could use it exactly how I would expect it to work.

Invoke-Expression $([System.IO.File]::ReadAllText('C:\Temp\myclass.txt'))
$NewStudent = [student]::new()
$NewStudent.FirstName = "bob"
$NewStudent.LastName = "Johson"
$NewStudent

A bit annoying, but it works.

CodePudding user response：

I agree with what Vivere commented and that you need to add constructor(s) to the class like:

class student {
    [string]$FirstName
    [string]$LastName

    # create an empty student object
    student () {}

    # overload to create a student object with just the firstname
    student ([string]$FirstName) {
        # simply return the current value of Count
        $this.FirstName = $FirstName
    }

    # overload to create a student object with both first and lastname
    student ([string]$FirstName, [string]$LastName) {
        # simply return the current value of Count
        $this.FirstName = $FirstName
        $this.LastName  = $LastName
    }
}

Use it like:

$student1 = [student]::new()
$student2 = [student]::new('Name1')
$student3 = [student]::new('Someone', 'Else')