On Jan 5, 2008 4:20 PM, Tim Peters <[EMAIL PROTECTED]> wrote:
> [Guido]
> > Wow. Do you have an opinion as to whether we should adopt
> > round-to-even at all (as a default)?
>
> Yes: yes :-)
Thanks for the suggestion, Tim. Here's a new proposed patch to the
pep. It still allows type-defined half-rounding behavior so that
Decimal can follow the current context. I'll submit it tomorrow unless
there are significant objections.
Index: pep-3141.txt
===================================================================
--- pep-3141.txt (revision 59739)
+++ pep-3141.txt (working copy)
@@ -205,8 +205,12 @@
def __round__(self, ndigits:Integral=None):
"""Rounds self to ndigits decimal places, defaulting to 0.
- If ndigits is omitted or None, returns an Integral, otherwise
- returns a Real. Rounds half toward even.
+ If ndigits is omitted or None, returns an Integral,
+ otherwise returns a Real, preferably of the same type as
+ self. Types may choose which direction to round half. For
+ example, float rounds half toward even, and Decimal rounds
+ it according to the current context.
+
"""
raise NotImplementedError
@@ -428,10 +432,14 @@
least Integral ``>= x``.
4. ``__round__(self)``, called from ``round(x)``, which returns the
- Integral closest to ``x``, rounding half toward even. There is also
- a 2-argument version, ``__round__(self, other)``, called from
- ``round(x, y)``, which should return a Real.
+ Integral closest to ``x``, rounding half as the type chooses.
+ ``float`` will change in 3.0 to round half toward even. There is
+ also a 2-argument version, ``__round__(self, ndigits)``, called
+ from ``round(x, ndigits)``, which should return a Real.
+In 2.6, ``math.floor``, ``math.ceil``, and ``round`` will continue to
+return floats.
+
Because the ``int()`` conversion implemented by ``float`` (and by
``decimal.Decimal``) is equivalent to but less explicit than
``trunc()``, let's remove it. (Or, if that breaks too much, just add a
--
Namasté,
Jeffrey Yasskin
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