diff options
Diffstat (limited to 'Doc/whatsnew')
| -rw-r--r-- | Doc/whatsnew/3.2.rst | 45 |
1 files changed, 37 insertions, 8 deletions
diff --git a/Doc/whatsnew/3.2.rst b/Doc/whatsnew/3.2.rst index 41e2e58..ed932ad 100644 --- a/Doc/whatsnew/3.2.rst +++ b/Doc/whatsnew/3.2.rst @@ -419,14 +419,6 @@ Some smaller changes made to the core Python language are: (Added by Antoine Pitrou; :issue:`9757`.) -* Mark Dickinson crafted an elegant and efficient scheme for assuring that - different numeric datatypes will have the same hash value whenever their - actual values are equal:: - - >>> assert hash(Fraction(3, 2)) == hash(1.5) == \ - hash(Decimal("1.5")) == hash(complex(1.5, 0)) - - (See :issue:`8188`.) * Previously it was illegal to delete a name from the local namespace if it occurs as a free variable in a nested block:: @@ -773,6 +765,43 @@ way to return a logging instance for use in the body of enclosed statements. (Contributed by Michael Foord in :issue:`9110`.) +decimal and fractions +--------------------- + +Mark Dickinson crafted an elegant and efficient scheme for assuring that +different numeric datatypes will have the same hash value whenever their actual +values are equal (:issue:`8188`):: + + >>> assert hash(Fraction(3, 2)) == hash(1.5) == \ + hash(Decimal("1.5")) == hash(complex(1.5, 0)) + +An early decision to limit the inter-operability of various numeric types has +been relaxed. It is still unsupported (and ill-advised) to to have implicit +mixing in arithmetic expressions such as ``Decimal('1.1') + float('1.1')`` +because the latter loses information in the process of constructing the binary +float. However, since existing floating point value can be converted losslessly +to either a decimal or rational representation, it makes sense to add them to +the constructor and to support mixed-type comparisons. + +* The :class:`decimal.Decimal` contructor now accepts :class:`float` objects + directly so there in no longer a need to use the :meth:`~decimal.Decimal.from_float` + method. + +* Mixed type comparisons are now fully supported so that + :class:`~decimal.Decimal` objects can be directly compared with :class:`float` + and :class:`fractions.Fraction`. + +Similar changes were made to :class:`fractions.Fraction` so that the +:meth:`~fractions.Fraction.from_float()` and :meth:`~fractions.Fraction.from_decimal` +methods are no longer needed. + +Another useful change for the :mod:`decimal` module is that the +:attr:`Context.clamp` attribute is now public. This is useful in creating +contexts that correspond to the decimal interchange formats specified in IEEE +754 (see :issue:`8540`). + +(Contributed by Mark Dickinson.) + ftp --- |