How to get the current directory of the cmdlet being executed

Question

This should be a simple task, but I have seen several attempts on how to get the path to the directory where the executed cmdlet is located with mixed success. For instance,

Answer 1

The easiest method seems to be to use the following predefined variable:

 $PSScriptRoot

about_Automatic_Variables and about_Scripts both state:

In PowerShell 2.0, this variable is valid only in script modules (.psm1). Beginning in PowerShell 3.0, it is valid in all scripts.

I use it like this:

 $MyFileName = "data.txt"
 $filebase = Join-Path $PSScriptRoot $MyFileName