On Wed, Dec 8, 2010 at 8:11 PM, <howit...@archlinux.us> wrote: > Hi. > > For the past week, I've been following an online Python guide named: > 'Learn Python the Hard Way'. I'm very happy with it as it gives a lot of > freedom to explore. > > However, due to this I have no idea if I'm thinking the right way. That's > why I've attached a script of mine I've been working on all day. > > It works a 100%, but I'm afraid I've made very bad choices concerning > design and coding style. (If it could've been much simpler, if there are > glaring mistakes, poor methods, ..) > > Could anyone be so friendly as to offer a bit of feedback, to a newbie? >
I like that you've divided the program up into functions, this is A Good Thing(TM). It made it much easier for me to understand what is going on, so keep doing that. little nitpick (maybe not *so* little), your functions are mutually recursive. This is a difficult word that basically means that they are all calling each other in a cycle that is potentially endless. In this case, the cycle goes like this: check_OP_size -> ask_change -> choice_result -> change_vars -> check_OP_size. You see that if I keep inputting the right things, I can go through this cycle endlessly. In this case, it's not a big problem, because no one is likely to do that for long enough to cause problems, but if another part of your program is doing the inputting, it can go wrong quickly. Why? Because functions can't call each other indefinitely. Try running this example: def f(): f() f() This is a function that keeps calling itself, the simplest possible cycle. It gives you an error "maximum recursion depth exceeded." There are reasons for this, and you should learn about recursion and the call stack at some point, but that is another long essay. For now it is enough to know that recursion is something to be careful with, as there is a limit to how many functions can call each other. Second, you're using globals too much. Functions should rely as much as possible on their arguments, and nothing else. I can count the number of times I needed the global statement on one hand, and I've programmed a lot of python. Globals make your program difficult to follow, because you can't clearly see where the data is coming from and going to. Rather than having your functions communicate through global variables, you should have them communicate through function arguments and return values. See if you can write a version without the global statements. There are a few other little things. The two if statements in check_OP_size can be rewritten into an if/else statement, since the two checks are complementary (one of them will always be true). The while loop in the_loop is a little overcomplicated (you had the right idea with the commented out range call). Lastly, the program could've been written a lot more succinctly, but this will come with time and practice. Writing code is hard, and getting a feel for how to divide up your functions and how to express yourself in python most naturally will take time and practice. I'd say you're on the right track, and if you get rid of all the globals you'll be well on your way to becoming an excelling python programmer. If you need any more help, let us know. Hugo _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
