On Sat, 24 Dec 2011 02:55:41 +1100, Chris Angelico wrote: > On Sat, Dec 24, 2011 at 2:49 AM, Steven D'Aprano > <steve+comp.lang.pyt...@pearwood.info> wrote: >> To fake early binding when the language provides late binding, you >> still use a sentinel value, but the initialization code creating the >> default value is outside the body of the function, usually in a global >> variable: >> >> _DEFAULT_Y = [] # Private constant, don't touch. >> >> def func(x, y=None): >> if y is None: >> y = _DEFAULT_Y >> ... >> >> This separates parts of the code that should be together, and relies on >> a global, with all the disadvantages that implies. > > A static variable (in the C sense) would make this just as clean as the > alternative. In Python, that could be implemented as an attribute of the > function object. Oh looky here... that's how default arguments are > implemented. :)
Yes. But having to manage it *by hand* is still unclean: * you still have to assign the default value to the function assignment outside the function, which is inelegant; * if you rename the function, the internal lookup func.default_value will fail. I'm not saying it can't be done. I'm just saying that the status quo is cleaner and more elegant, and if you want late binding, there is a simple, obvious, elegant idiom to get it. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
