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

Jeffrey Yasskin jyasskin at gmail.com
Mon Jan 7 06:54:30 CET 2008

On Jan 6, 2008 7:40 PM, Raymond Hettinger <python at rcn.com> wrote:

[Jeffrey Yasskin] > The other 3 methods > specified by PEP 3141 aren't strictly necessary for 2.6, but they will > be needed for 3.0. I'd rather not make the two versions of Decimal > gratuitously different, so this patch puts them in the 2.6 version > too.

If I understand you correctly, then the patch backports magic methods that do not have corresponding invocation methods in Py2.6. So, they are basically useless. If that's true, then the patch is clutter -- it makes 2.6 less desirable. It is not obvious to me how this will help someone transition to Py3.0. I'm curious to hear how Guido makes the call on this. Also, the goal of keeping versions identical across 2.6 and 3.0 is at odds with previous discussions where I believe we said that that is not the goal and will likely not even be possible in many cases. Besides, if the invocation of the magic methods is different in 3.0, how are you going to keep the test suite code the same across versions?

Given Guido's agreement, expect another version of this patch with only trunc.

There should probably be a PEP sets clearer guidelines about what should be backported from Py3.0. Perhaps something like this: * If there is a new feature that can be implemented in both and will make both more attractive, then it should be in both. * If something is going away or changing in 3.0, then the 2.6 conversion tool mode should warn about it if possible. * If neither of the above apply, then leave 2.6 alone.

> I'm not > sure exactly what you're objecting to. Could you be more precise? You note said: "I'll implement Context.round() in a separate patch. Comment away."

Oh, sorry for not being clear then. I don't intend to write or discuss that separate patch until this one's approved and submitted. I think it's worth discussing eventually, but this change is more important. I mentioned this sentiment at http://bugs.python.org/msg59417 too, but clearly wasn't explicit enough in either case.

-- Namasté, Jeffrey Yasskin

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