Powershell class implement get set property - powershell

Question

How can I implement a get/set property with PowerShell class?
Please have a look on my example below:
Class TestObject
{
[DateTime]$StartTimestamp = (Get-Date)
[DateTime]$EndTimestamp = (Get-Date).AddHours(2)
[TimeSpan] $TotalDuration {
get {
return ($this.EndTimestamp - $this.StartTimestamp)
}
}
hidden [string] $_name = 'Andreas'
[string] $Name {
get {
return $this._name
}
set {
$this._name = $value
}
}
}
New-Object TestObject

Answer 1

You can use Add-Member ScriptProperty to achieve a kind of getter and setter:
class c {
hidden $_p = $($this | Add-Member ScriptProperty 'p' `
{
# get
"getter $($this._p)"
}`
{
# set
param ( $arg )
$this._p = "setter $arg"
}
)
}
Newing it up invokes the initializer for $_p which adds scriptproperty p:
PS C:\> $c = [c]::new()
And using property p yields the following:
PS C:\>$c.p = 'arg value'
PS C:\>$c.p
getter setter arg value
This technique has some pitfalls which are mostly related to how verbose and error-prone the Add-Member line is. To avoid those pitfalls, I implemented Accessor which you can find here.
Using Accessor instead of Add-Member does an amount of error-checking and simplifies the original class implementation to this:
class c {
hidden $_p = $(Accessor $this {
get {
"getter $($this._p)"
}
set {
param ( $arg )
$this._p = "setter $arg"
}
})
}

Answer 2

Here's how I went about it
[string]$BaseCodeSignUrl; # Getter defined in __class_init__. Declaration allows intellisense to pick up property
[string]$PostJobUrl; # Getter defined in __class_init__. Declaration allows intellisense to pick up property
[hashtable]$Headers; # Getter defined in __class_init__. Declaration allows intellisense to pick up property
[string]$ReqJobProgressUrl; # Getter defined in __class_init__. Declaration allows intellisense to pick up property
# Powershell lacks a way to add get/set properties. This is a workaround
hidden $__class_init__ = $(Invoke-Command -InputObject $this -NoNewScope -ScriptBlock {
$this | Add-Member -MemberType ScriptProperty -Name 'BaseCodeSignUrl' -Force -Value {
if ($this.Production) { [CodeSign]::CodeSignAPIUrl } else { [CodeSign]::CodeSignTestAPIUrl }
}
$this | Add-Member -MemberType ScriptProperty -Name 'PostJobUrl' -Force -Value {
"$($this.BaseCodeSignUrl)/Post?v=$([CodeSign]::ServiceApiVersion)"
}
$this | Add-Member -MemberType ScriptProperty -Name 'Headers' -Force -Value {
#{
_ExpireInMinutes=[CodeSign]::Timeout.Minutes;
_CodeSigningKey=$this.Key;
_JobId=$this.JobId;
_Debug=$this.Dbg;
_Token=$this.Token;
}
}
$this | Add-Member -MemberType ScriptProperty -Name 'ReqJobProgressUrl' -Force -Value {
"$($this.BaseCodeSignUrl)Get?jobId=$($this.JobId)"
}
});