Steven D'Aprano <st...@pearwood.info> wrote: >> To properly handle int and float subclasses, int(), index(), and float() >> will be called on the objects intended for (d, i, u), (b, o, x, X), and >> (e, E, f, F, g, G). > > > -1 on this idea. > > This is a rather large violation of the principle of least surprise, and > radically different from the behaviour of Python 3 str. In Python 3, > '%d' interpolation calls the __str__ method, so if you subclass, you can > get the behaviour you want: > > py> class HexInt(int): > ... def __str__(self): > ... return hex(self) > ... > py> "%d" % HexInt(23) > '0x17' > > > which is exactly what we should expect from a subclass. > > You're suggesting that bytes should ignore any custom display > implemented by subclasses, and implicitly coerce them to the superclass > int. What is the justification for this? You don't define or even > describe what you consider "properly handle".
The proposed behavior (at least as I understand it and as I've implemented in my proposed patch) matches Python 2 str/unicode and Python 3 str behavior for these codes. If you want to allow subclasses to have control or to use duck-typing, you have to use str and __format__. I'm okay with the limitation, bytes formatting can be simple, limited and fast. Neil _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
