On Sat, Oct 3, 2009 at 11:29 PM, horos11 <horo...@gmail.com> wrote: > All, > > Another one, this time a bit shorter. > > It looks like defaults for arguments are only bound once, and every > subsequent call reuses the first reference created. Hence the > following will print '[10,2]' instead of the expected '[1,2]'. > > Now my question - exactly why is 'default_me()' only called once, on > the construction of the first object?
Actually, the single call happens at the "definition-time" of the function. As for why, it's less magical than re-evaulating it on every function call when that parameter is not supplied a value; trust me, the issue has been argued to death. > And what's the best way to get > around this if you want to have a default for an argument which so > happens to be a reference or a new object? See http://docs.python.org/tutorial/controlflow.html#default-argument-values Essentially, use None as the default value, then check for it and assign the real default value in the function body. Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
