Is there a proper way to create a scriptproperty in a Powershell 5 class

Question

In Powershell versions prior to 5, objects could be created "on the go" with New-Object, and could be extended with Add-Member. Powershell 5 introduced classes, but it seems they only allow basic properties and methods. Is there any proper way one can emulate a scriptproperty (IE. a property that is seen as a property, not as a method, but is still calculated on the go)?

The following code gives the wanted result thanks to a hack in the constructor. Can this hack be avoided?

class fakescriptproperty {
    hidden [datetime] _currenttime() { return ( Get-Date ) }

    fakescriptproperty() {
        Add-Member -InputObject $this -MemberType ScriptProperty `
            -Name currenttime -Value { $this._currenttime() }
    }
}

$test = New-Object -TypeName fakescriptproperty
$test.currenttime

Answer 1

not sure I understand the problem here. This is how I create, extend and access custom objects; let me know if you're after something else.

# Creating new object with key/value hashtable
$customObject = New-Object psobject -Property @{key1 = "value" ; key2 = "value2"}

# Adding member to custom object
$customObject | Add-Member -MemberType NoteProperty -Name key3 -Value value3

# This will return value3
$customObject.key3

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Edit - I'm not familiar with classes. In PowerShell 5 it is possible to extend custom objects with a ScriptProperty member and specify a scriptblock that is calculated on the go (no hackery required).

$test = New-Object psobject
$test | Add-Member -Name currentime -MemberType ScriptProperty -Value {Get-Date}
$test.currentime

It is possible to specify a -SecondValue scriptblock that handles setting the property (keep running into StackOverflowException when testing this)