On Sun, 25 Jan 2009 12:01:16 -0800, Russ P. wrote: > On Jan 25, 10:04 am, Mark Wooding <m...@distorted.org.uk> wrote: > >> > But what if I want an automatic check to verify that I am using it as >> > the author intended? Is that unreasonable? >> >> You mean that you can't /tell/ whether you typed mumble._seekrit? >> You're very strange. It's kind of hard to do by accident. > > But what if you type "mumble._seekrit" in several places, then the > library implementer decides to give in to your nagging and makes it > "public" by changing it to "mumble.seekrit". Now suppose you forget to > make the corresponding change somewhere in your code, such as > > mumble._seekrit = zzz > > You will get no warning at all. You will just be inadvertently creating > a new "private" attribute -- and the assignment that you really want > will not get done. > > For that matter, the library implementer himself could make the same > mistake and get no warning. > > When you think about it, you soon realize that the leading underscore > convention violates the spirit if not the letter of one of the first > principles of programming 101: if you have a constant parameter that > appears in several places, assign the literal value in one place rather > than repeating it everywhere. Then if you need to change the value, you > only need to change it in one place. That reduces effort, but more > importantly it reduces the potential for error.
How is this scenario different from an API change where public_method() gets changed to method()? Surely this is just a downside to Python's lack of declarations, rather than specific to Python's lack of data hiding? -- Steven -- http://mail.python.org/mailman/listinfo/python-list
