Frequently, Add-Member is used to create custom objects, for example like this:
$o = New-Object -TypeName PSObject $o | Add-Member -MemberType NoteProperty -Name Notes -Value 'Something' $o | Add-Member -MemberType NoteProperty -Name Date -Value (Get-Date) $o
This works, and the result looks like this:
PS C:\> $o Notes Date ----- ---- Something 10/28/2016 3:56:53 PM
However, it is inefficient because Add-Member is used to dynamically extend existing objects, not to create new ones. The above could much more easily be achieved like this:
$o = [PSCustomObject]@{ Notes = 'Something' Date = Get-Date } $o
Add-Member can do much more advanced things, like adding script properties and methods. Check out what happens when you add a dynamic script property to above object:
$o = [PSCustomObject]@{ Notes = 'Something' Date = Get-Date } $o | Add-Member -MemberType ScriptProperty -Name CurrentDate -Value { Get-Date }
Now watch the Date and CurrentDate properties when you query the object multiple times:
PS C:\> $o Notes Date CurrentDate ----- ---- ----------- Something 10/28/2016 4:01:54 PM 10/28/2016 4:01:57 PM PS C:\> $o Notes Date CurrentDate ----- ---- ----------- Something 10/28/2016 4:01:54 PM 10/28/2016 4:02:00 PM PS C:\> $o Notes Date CurrentDate ----- ---- ----------- Something 10/28/2016 4:01:54 PM 10/28/2016 4:02:02 PM
While Date property returns a static information, CurrentDate property always reports the current time because its value is a script that gets executed each time someone queries the property.
