[Python-Dev] Mixing float and Decimal -- thread reboot

Guido van Rossum guido at python.org
Mon Mar 22 20:52:24 CET 2010

On Mon, Mar 22, 2010 at 11:36 AM, Raymond Hettinger
<raymond.hettinger at gmail.com> wrote:
> One other thought.
> The Decimal constructor should now accept floats as a possible input type.
> Formerly, we separated that out to Decimal.from_float() because
> decimals weren't interoperable with floats.

Not sure this follows; Fraction(1.1) raises an exception, you have to
use Fraction.from_float().

> This will put decimal and float back on equal footing so that we have both:
>    float(some_decimal)        # coerce to binary float
> and
>    Decimal(some_float)       # coerce to decimal float

If you really want this I won't stop you.

> That will also save us from odd idioms like:
>    d = some_float + Decimal(0)   # coerce to decimal then apply context rounding

Although this isn't too bad:

  d = Decimal.from_float(some_float)

> This also matches the behavior of other constructors:
>    int(some_float)
> or
>    int(some_decimal)
> or
>    str(some_float)
> or
>    str(some_decimal)

True, I don't care strongly.

--Guido van Rossum (python.org/~guido)

More information about the Python-Dev mailing list