[Python-Dev] Decimal & amp; lt; -& amp; gt; float comparisons in py3k. (original) (raw)

Nick Coghlan ncoghlan at gmail.com
Sun Mar 21 02:10:08 CET 2010


Greg Ewing wrote:

Antoine Pitrou wrote:

We forbid comparisons when there is a real danger or ambiguity, such as unicode vs. bytes. There is no such danger or ambiguity when comparing a decimal with a float. So do you think that float("0.1") and Decimal("0.1") should be equal or not, and why?

Note that Antoine's point was that float("0.1") and Decimal.from_float(0.1) should compare equal. The latter exactly matches the underlying binary floating point value:

dec.fromfloat(0.1) Decimal('0.1000000000000000055511151231257827021181583404541015625')

Cheers, Nick.

-- Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia



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