This issue tracker has been migrated to GitHub, and is currently read-only.
For more information, see the GitHub FAQs in the Python's Developer Guide.

Author larry
Recipients Alexander.Belopolsky, Arfrever, belopolsky, jcea, khenriksson, larry, lars.gustaebel, loewis, mark.dickinson, nadeem.vawda, r.david.murray, rosslagerwall, skrah, vstinner
Date 2011-09-09.22:18:13
SpamBayes Score 2.0187825e-07
Marked as misclassified No
Message-id <>
I've drawn an ASCII table summarizing the proposals so far.  If I've made any factual errors I trust you'll let me know.

=<type> means os.stat().st_mtime is changed to that type.
+<type> means os.stat() grows a new field using that type,
  and the current behavior of st_mtime is unchanged.


[ UPSIDES      ]        =(int,int)  +(int,int) =Decimal +Decimal =float128
[ yes is good! ]

all existing code gets   no           no        no       no       yes
more accurate for free

some existing code gets  no           no        yes      no       yes
more accurate for free

future-proof against     no           no        yes      yes      no*
new representations

very very
future-proof against     no           no        yes      yes      yes*
new representations

* float128 could handle representations finer than yoctosecond resolution,
  10**-24, but not another 10**-3.  fwiw, yocto is currently the smallest
  defined prefix.

[ DOWNSIDES   ]          =(int,int)  +(int,int) =Decimal +Decimal =float128
[ yes is bad! ]

breaks existing code      yes          no        yes      no       no

requires new code in
order to take advantage   yes*         yes       yes*     yes      no
of added precision

requires implementing a   no           no        no       no       yes
complicated new type

* Since this option breaks existing code, obviously people will have to
  write new code in order to cope.

My take on the above: if we're willing to put people through the pain of changing their code to use the new accuracy, then Decimal is the obvious winner.  I see no advantage to any of the pair-of-floats proposals over Decimal.

If we want all existing code to continue working and get more accurate automatically, the only viable option is float128 (or a multiple-precision float).
Date User Action Args
2011-09-09 22:18:14larrysetrecipients: + larry, loewis, jcea, mark.dickinson, belopolsky, lars.gustaebel, vstinner, nadeem.vawda, Arfrever, r.david.murray, skrah, Alexander.Belopolsky, rosslagerwall, khenriksson
2011-09-09 22:18:14larrysetmessageid: <>
2011-09-09 22:18:14larrylinkissue11457 messages
2011-09-09 22:18:13larrycreate