[issue10650] decimal.py: quantize(): excess digits with watchexp=0
Roundup Robot added the comment: New changeset c2f827af02a2 by Stefan Krah in branch 'default': Issue #10650: Remove the non-standard 'watchexp' parameter from the http://hg.python.org/cpython/rev/c2f827af02a2 -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10650 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue10650] decimal.py: quantize(): excess digits with watchexp=0
Roundup Robot added the comment: New changeset e4ca4edee8bd by Stefan Krah in branch 'default': Closes #10650: Deprecate the watchexp parameter of Decimal.quantize(). http://hg.python.org/cpython/rev/e4ca4edee8bd -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10650 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue10650] decimal.py: quantize(): excess digits with watchexp=0
Stefan Krah added the comment: Here's a patch deprecating watchexp. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10650 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue10650] decimal.py: quantize(): excess digits with watchexp=0
Changes by Stefan Krah stefan-use...@bytereef.org: -- keywords: +patch Added file: http://bugs.python.org/file26996/issue10650.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10650 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue10650] decimal.py: quantize(): excess digits with watchexp=0
Stefan Krah stefan-use...@bytereef.org added the comment: watchexp was available in rescale() from the beginning ... http://svn.python.org/view/sandbox/trunk/decimal/Decimal.py?revision=40721view=markup ... and rescale() was renamed to quantize() in http://svn.python.org/view/sandbox/trunk/decimal/Decimal.py?revision=40909view=markup rescale() was once part of the specification, but had identical semantics to quantize(), which is not specified to allow unlimited rescaling. I suppose the original rescale() in the sandbox had watchexp for convenience, in order to avoid two separate functions. watchexp made it into quantize(), probably because people thought there is a need for unlimited rescaling. This may be true, but I'd really prefer to expose rescale() as the unlimited version then. While it's unusual to just drop an API without deprecation, I think it's OK in this instance: Virtually all decimal code I saw needs to be cleaned up anyway because it uses tons of underscore methods from decimal.py. The only thing that worries me is that there might be code which *really* needs unlimited rescaling. Such code could of course also use a temporary context. So I propose this: Deprecate watchexp and leave it in the Python version for one release. The C version won't have watchexp from the start. After all, PEP-399 allows accelerator modules to implement a subset of the functionality of the Python version -- sometimes PEPs are a wonderful thing :). -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10650 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue10650] decimal.py: quantize(): excess digits with watchexp=0
Stefan Krah stefan-use...@bytereef.org added the comment: Ping. We have to decide if we need watchexp in _decimal. I've left it out so far since all I can gather from the docs is that it somehow behaves like _rescale. Can we deprecate it and replace it by a proper rescale? -- nosy: +georg.brandl ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10650 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue10650] decimal.py: quantize(): excess digits with watchexp=0
Mark Dickinson dicki...@gmail.com added the comment: I'd be happy to see watchexp deprecated. It feels like a leftover implementation artefact; its behaviour isn't properly defined anywhere, and as far as I can tell it has only a single testcase. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10650 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue10650] decimal.py: quantize(): excess digits with watchexp=0
Raymond Hettinger raymond.hettin...@gmail.com added the comment: Does anyone know why watchexp was put there in the first place? http://speleotrove.com/decimal/daops.html#refquant If no motivation for this can be found, I agree with Mark that it should be deprecated and removed. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10650 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue10650] decimal.py: quantize(): excess digits with watchexp=0
New submission from Stefan Krah stefan-use...@bytereef.org:
I'm not sure if this is a documentation issue or a bug. If watchexp=0,
quantize() also allows any number of digits:
x = Decimal(6885998238912213556789006667970467609814)
y = Decimal(1e2)
x.quantize(y)
Traceback (most recent call last):
File stdin, line 1, in module
File /usr/local/lib/python3.2/decimal.py, line 2488, in quantize
'quantize result has too many digits for current context')
File /usr/local/lib/python3.2/decimal.py, line 3925, in _raise_error
raise error(explanation)
decimal.InvalidOperation: quantize result has too many digits for current
context
x.quantize(y, watchexp=0)
Decimal('6.8859982389122135567890066679704676098E+39')
--
components: Library (Lib)
messages: 123603
nosy: mark.dickinson, rhettinger, skrah
priority: normal
severity: normal
status: open
title: decimal.py: quantize(): excess digits with watchexp=0
type: behavior
versions: Python 2.7, Python 3.1, Python 3.2
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[issue10650] decimal.py: quantize(): excess digits with watchexp=0
Stefan Krah stefan-use...@bytereef.org added the comment:
NaNs, however, are decapitated:
x = Decimal(NaN5357671565858315212612021522416387828577)
y = 0
x.quantize(y, watchexp=0)
Decimal('NaN8315212612021522416387828577')
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