[Python-Dev] [Python-3000] Rounding Decimals (original) (raw)

Aahz aahz at pythoncraft.com
Mon Jan 7 16:53:26 CET 2008

On Mon, Jan 07, 2008, Raymond Hettinger wrote:

[Jeffrey Yasskin]

I am not building out the decimal API. I am adding enough methods to maintain the comment that "Decimal floating point objects share many properties with the other builtin numeric types such as float and int. All of the usual math operations and special methods apply." in both 2.6 and 3.0. After that's done, I am interested in talking about adding one method that 3 people on this list have been interested in. I understand that you need to be vigilant against extraneous methods, but I'm really not just adding these on a whim. Arghh! You seem hell-bent on jamming this in. Please leave the decimal module alone. It does not need both a round() method and a quantize() method. I read Glyph's note and agree that it wasn't obvious how to round with the existing API. That is a documentation problem, not a call to add duplicate methods.

Excuse me. I have always thought that "quantize()" makes Decimal confusing in the context of the other mechanisms that Python makes available for other kinds of numbers. I have refrained from making an issue of it because I understand and (mostly) support the idea of keeping Decimal restricted to matching the decimal standard, but at this point, it seems that Tim Peters likes the idea, too. While I have a lot of respect for you, I think Uncle Timmy deserves some special respect, too.

When one of the module authors asks you to refrain for expanding the API, please pay special attention. In this case, you are working directly against a core philosophy for the design and maintenance of the module.

I'm not a current maintainer, but I was one of the instigators for the existence of Decimal. I understand that you're feeling frustrated about changes getting shoved in, but I don't think that discussion should be shut down because you have a particular point of view: the decimal module does not represent only your work.

I suggest that the patches get dropped for the moment and the discussion rebooted. I haven't been following closely, but it seems that the main issue is that Python 3.0 is introducing a round() method. How do you think the decimal module should handle that? (Although I still like the idea of a .round() method for decimals, I think that round(Decimal()) is probably sufficient enough that I won't insist on it.)

Aahz (aahz at pythoncraft.com) <*> http://www.pythoncraft.com/

Weinberg's Second Law: If builders built buildings the way programmers wrote programs, then the first woodpecker that came along would destroy civilization.

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