[Python-Dev] PEP 0484 - the Numeric Tower (original) (raw)

Laura Creighton lac at openend.se
Tue Oct 13 12:46:55 EDT 2015

In a message of Tue, 13 Oct 2015 08:38:07 -0700, Raymond Hettinger writes:

On Oct 13, 2015, at 4:21 AM, Laura Creighton <lac at openend.se> wrote: Any chance of adding Decimal to the list of things that are also acceptable for things annotated float? From Lib/numbers.py: ## Notes on Decimal ## ---------------- ## Decimal has all of the methods specified by the Real abc, but it should ## not be registered as a Real because decimals do not interoperate with ## binary floats (i.e. Decimal('3.14') + 2.71828 is undefined). But, ## abstract reals are expected to interoperate (i.e. R1 + R2 should be ## expected to work if R1 and R2 are both Reals). That is still true: Python 3.5.0 (v3.5.0:374f501f4567, Sep 12 2015, 11:00:19) [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin Type "copyright", "credits" or "license()" for more information. from decimal import Decimal Decimal('3.14') + 2.71828 Traceback (most recent call last): File "<pyshell#1>", line 1, in Decimal('3.14') + 2.71828 TypeError: unsupported operand type(s) for +: 'decimal.Decimal' and 'float' Raymond Hettinger

I take it that is a 'no'. I merely worry about what hapens if people start relying upon the fact that a float annotation 'will handle all the numbers I care about' to the forgotten Decimal users such as myself.

Laura

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