because the prior versions of this book were widely readhere is quick rundown of some of the most prominent specific changes in this editionits existing material was shortened to allow for new topics the prior edition of this book was also -page volumewhich didn' allow much room for covering new python topics (python ' unicode orientation alone implies much new materialluckilyrecent changes in the python world have allowed us to pare down some less critical existing material this time aroundin order to free up room for new coverage depth was not sacrificed in the processof courseand this is still just as substantial book as before in generalthoughavoiding new growth was primary goal of this updatemany of the other specific changes and removals 'll mention below were madein partto help accommodate new topics it covers (onlythis book' examples and narrative have been updated to reflect and use the version of python python is no longer supported hereexcept where and pythons overlap although the overlap is large enough to make this of use to readers toothis is now officially -only text this turns out to be major factor behind the lack of growth in this edition by restricting our scope to python --the incompatible successor to the python lineand considered to be python' future--we were able to avoid doubling the coverage size in places where the two python lines differ this version limit is especially important in book like this that is largely about more advanced exampleswhich can be listed in only one version' style for readers who still straddle the and worldsi'll say more about python changes later in this preface probably the most significant -related change described there is the new internationalization support in pyedit and pymailguithough had unicode tooits new prominence in almost forces such systems to rethink their former ascii-only ways inclusion of newly emerged libraries and tools since the prior editiona variety of new libraries and tools have either come online or risen in popularityand they get new mention here this includes new standard library tools such as subprocess (in and and multiprocessing (in )as well as new third-party web frameworks and orm database toolkits most of these are not covered extensively (many popular third-party extensions are complex systems in their own right and are best covered by dedicated books)but they are at the least introduced in summary form here for examplepython ' new tkinter ttk tk themed widget set shows up in nowbut only brieflyas rulethis edition prefers to mention such extensions in passingrather than attempting to show you code without adequate explanation xxvi preface