[Python-Dev] Return type of round, floor, and ceil in 2.6 (original) (raw)

glyph at divmod.com glyph at divmod.com
Sat Jan 5 23:54:15 CET 2008

On 04:54 pm, guido at python.org wrote:

On Jan 4, 2008 10:16 PM, <glyph at divmod.com> wrote:

Having other rounding methods available, though, would be neat. The only application I've ever worked on where I cared about the difference, the user had to select it (since accounting requirements differ by jurisdiction and, apparently, by bank preference). Having a standard way to express this (especially if it worked across different numeric types, but perhaps I digress) would be pleasant. Implementing stochastic rounding and banker's rounding oneself, while not exactly hard, is a drag. The decimal module already supports rounding modes in its context. For other types, perhaps converting to decimal might be good enough?

Yes, that's the right thing to do. I had missed it. After all it is decimal rounding I want, and any financial applications I'm going to write these days are using decimals already for all the usual reasons.

At first I didn't realize why I'd missed this feature. While the rounding modes are well documented, though, after 20 minutes of reading documentation I still haven't found a method or function that simply rounds a decimal to a given significant digit. Is there one, should there be one, or is the user simply meant to use Context.quantize with appropriate arguments?

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