[MrDosu]

There are multiple approaches (my favs being dependency injection or aspect oriented). The actual case of a dependency affecting an entire application is called a "cross cutting concern", there is great literature to be found under that term that explains it better then I ever could. It highly depends on the use case though, just have it in your toolbox (and dont get in the habit of argueing when you are tasked to build a house whether you should use the hammer OR the saw like some peeps in this thread. Select the right tool for the right circumstance dont just limit yourself to one).