In article <[EMAIL PROTECTED]>, Ron_Adam <[EMAIL PROTECTED]> wrote: >On Tue, 29 Mar 2005 09:09:37 -0500, Charles Hartman ><[EMAIL PROTECTED]> wrote: > >>I know the answer to this is going to be "It depends . . .", but I want >>to get my mind right. In Fowler's *Refactoring* I read: "Older >>languages carried an overhead in subroutine calls, which deterred >>people from small methods" (followed by the basic "Extract Method" >>advice). In Skip Montanaro's "Python Performance Tips" >>(http://manatee.mojam.com/~skip/python/fastpython.html) I read: ". . . >>use local variables wherever possible. If the above loop is cast as a >>function, append and upper become local variables. Python accesses >>local variables much more efficiently than global variables." >> >>These two pieces of advice imply opposite kinds of code revisions. >>Obviously they have different purposes, and both are right at different >>times. I wonder if anyone has some wisdom about how to think about when >>or how often to do which, how to balance them ultimately, and so on. >> >>Charles Hartman >>Professor of English, Poet in Residence >>the Scandroid is at: http://cherry.conncoll.edu/cohar/Programs >>http://villex.blogspot.com > > >It depends... ;) > >Converting small functions to inline, usually should only be done in >the inner most loops to optimize performance if it's needed. Moving >calculations out of those loops by doing them ahead of time is also >good. > >It's good practice in python to put all of your code in functions or >class's even if it's a single main() function. > >def main() > (program code) > >main() > >Then you avoid the slower globals unless you declare them with the >global statement. > >If main, or any other functions, get too big or complex, split them up >as needed. . . . I follow-up in part for the opportunity to address a Poet-in-residence.
I don't understand the claim that, "These two pieces of advice imply opposite ..." actions. In any case, I urge you to adopt the rule: when in doubt, write a function (or method). If you hesitate at all, that's evidence that you'll eventually be thankful you invested the effort explicitly to name a function (or method). Also, I strongly recommend to you the *Python Cookbook* <URL: http://www.oreilly.com/catalog/pythoncook2/ >. Make sure you get the second edition. It will delight you more than you imagined a computing book could. I applaud Ron's advice to define a main(). As soon as possible, I also want you to learn the "if __name__ == '__main__':", doctest, and pydoc idioms; I suspect you'll find them all invaluable. -- http://mail.python.org/mailman/listinfo/python-list
