Greetings, The site in question ( http://osl.iu.edu/~lums/swc/ ) is listed at ( http://python.org/ ) on the right-hand sidebar entitled: Using Python For...
# Education # pyBiblio, Software Carpentry Course Perhaps these concerns should be directed to either the maintainers of Python.Org ( http://python.org/ ), or to the author of the Software Carpentry Course? The course is available under an open license, AND This work [SWC] has been made possible by a grant from the Python Software Foundation, and by support from the University of Toronto. Your concerns sound serious enough to warrant corrections being made to the tutorial? -- bhaaluu at gmail dot com On 8/16/07, wesley chun <[EMAIL PROTECTED]> wrote: > > Python copies variables' values when passing them to functions > > a.. Since Booleans, numbers, and strings can't be updated, a > > function can't affect its caller's values > > b.. But if you pass a list to a function, the function will operate > > on the original list, not a copy > > ---------------- > > > > The first line is plain wrong. Python doesn't copy values it always uses > > references, > > its just that some objects are immutable while others are mutable. This is a > > common cause of confusion for beginners and this statement won't help. And > > the last line suggests that Python behaves inconsistently (which it > > doesn't) but > > doesn't clarify any of the "exceptions" other than lists - the same is > > actually > > true of any mutable type > > > i completely agree with alan on this. whoever wrote it does *not* > know Python very well. they seem to be "guessing" based on their > previous experience with other programming languages that are > "categorized" into either "call by reference" or "call by value". > > in python, *everything* is call by reference, but the reality is that > the mutability is the real source of truth. a simple call to id() > from the caller and the called function will show that they are indeed > the exact same object. (why else would i spend an entire chapter on > this in Core Python?!?) getting confused by both of these (call by XX > vs. mutability) is the source of many many bugs in Python, and if you > can get past this, those bugs would never exist (or have never > existed), leaving you in a much more peaceful state of mind. :-) > > cheers, > -- wesley > - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - > "Core Python Programming", Prentice Hall, (c)2007,2001 > http://corepython.com > > wesley.j.chun :: wescpy-at-gmail.com > python training and technical consulting > cyberweb.consulting : silicon valley, ca > http://cyberwebconsulting.com > _______________________________________________ > Tutor maillist - Tutor@python.org > http://mail.python.org/mailman/listinfo/tutor > _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
