Since a long time companies all over have found it suitable to use “PAC” (proxy auto-config) scripts to control browsers and tell them what proxy to use for what particular URL and more, and this has been a major nuisance for people who use other (automated) means to go through the proxy than one of them huge gui-based browsers.
For a long time, Ralph Mitchell’s take on this was the only half-decent way to get it working. Half-decent only because it was never packaged and provided in a convenient way to people, it was fully functional.
Now, Manu Garg seems to have stepped forward and introduces pacparser which is a C library for parsing PAC files. Period. It looks (very) similar to Ralph’s approach, in that it incorporates the Mozilla’s javascript engine Spidermonkey, with nothing really special added. So, it’s basically the same approach but this time it is packaged, shipped and documented how it is used!