It seems like this could be something similar to `functools.total_ordering` and decorate a class. In principle that transformation could go in either direction, but only if the decorator is used.
On Sat, Sep 17, 2016 at 3:56 AM, Mark Dickinson <dicki...@gmail.com> wrote: > On Sat, Sep 17, 2016 at 10:01 AM, Spencer Brown <spencer...@live.com> > wrote: > > Currently, calling divmod() on a class with __floordiv__ and __mod__ > > defined, but not __divmod__ raises a TypeError. Is there any reason why > it > > doesn't fallback to (self // x, self % x)? > > It's an interesting idea. I wonder whether the falling back shouldn't > be in the other direction, though: that is, if a class defines > `__divmod__` but not `__floordiv__` or `__mod__`, perhaps the `//` and > `%` operations should use `__divmod__`? That way, if you're writing a > class that intends to support all three operations, you only have to > write one method. And it might make sense from an efficiency > perspective, too; it's common for a `divmod` computation to be cheaper > than doing separate computations of the quotient and remainder. > > For the builtin int type, for example, in nontrivial cases Python > computes both the quotient and remainder when asked to do a % or // > operation, and then discards whichever part isn't needed. So in that > case it would be wasteful to build up the divmod result from two > separate % and // calls. > > -- > Mark > _______________________________________________ > Python-ideas mailing list > Pythonemail@example.com > https://mail.python.org/mailman/listinfo/python-ideas > Code of Conduct: http://python.org/psf/codeofconduct/ > -- Keeping medicines from the bloodstreams of the sick; food from the bellies of the hungry; books from the hands of the uneducated; technology from the underdeveloped; and putting advocates of freedom in prisons. Intellectual property is to the 21st century what the slave trade was to the 16th.
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