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Close #18738: Route __format__ calls to mixed-in type for mixed Enums (such as IntEnum).

This commit is contained in:
Ethan Furman 2013-08-31 19:17:41 -07:00
parent 34567ec94b
commit ec15a826ce
3 changed files with 122 additions and 4 deletions
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6
Doc/library/enum.rst
View File

@ -463,6 +463,12 @@ Some rules:
3. When another data type is mixed in, the :attr:`value` attribute is *not the
same* as the enum member itself, although it is equivalant and will compare
equal.
4. %-style formatting: `%s` and `%r` call :class:`Enum`'s :meth:`__str__` and
:meth:`__repr__` respectively; other codes (such as `%i` or `%h` for
IntEnum) treat the enum member as its mixed-in type.
5. :class:`str`.:meth:`__format__` (or :func:`format`) will use the mixed-in
type's :meth:`__format__`. If the :class:`Enum`'s :func:`str` or
:func:`repr` is desired use the `!s` or `!r` :class:`str` format codes.
Interesting examples

18
Lib/enum.py
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@ -50,7 +50,6 @@ def _make_class_unpicklable(cls):
cls.__reduce__ = _break_on_call_reduce
cls.__module__ = '<unknown>'
class _EnumDict(dict):
"""Keeps track of definition order of the enum items.
@ -182,7 +181,7 @@ class EnumMeta(type):
# double check that repr and friends are not the mixin's or various
# things break (such as pickle)
for name in ('__repr__', '__str__', '__getnewargs__'):
for name in ('__repr__', '__str__', '__format__', '__getnewargs__'):
class_method = getattr(enum_class, name)
obj_method = getattr(member_type, name, None)
enum_method = getattr(first_enum, name, None)
@ -441,6 +440,21 @@ class Enum(metaclass=EnumMeta):
return self is other
return NotImplemented
def __format__(self, format_spec):
# mixed-in Enums should use the mixed-in type's __format__, otherwise
# we can get strange results with the Enum name showing up instead of
# the value
# pure Enum branch
if self._member_type_ is object:
cls = str
val = str(self)
# mix-in branch
else:
cls = self._member_type_
val = self.value
return cls.__format__(val, format_spec)
def __getnewargs__(self):
return (self._value_, )

102
Lib/test/test_enum.py
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@ -67,6 +67,33 @@ class TestEnum(unittest.TestCase):
WINTER = 4
self.Season = Season
class Konstants(float, Enum):
E = 2.7182818
PI = 3.1415926
TAU = 2 * PI
self.Konstants = Konstants
class Grades(IntEnum):
A = 5
B = 4
C = 3
D = 2
F = 0
self.Grades = Grades
class Directional(str, Enum):
EAST = 'east'
WEST = 'west'
NORTH = 'north'
SOUTH = 'south'
self.Directional = Directional
from datetime import date
class Holiday(date, Enum):
NEW_YEAR = 2013, 1, 1
IDES_OF_MARCH = 2013, 3, 15
self.Holiday = Holiday
def test_dir_on_class(self):
Season = self.Season
self.assertEqual(
@ -207,6 +234,77 @@ class TestEnum(unittest.TestCase):
self.assertIs(type(Huh.name), Huh)
self.assertEqual(Huh.name.name, 'name')
self.assertEqual(Huh.name.value, 1)
def test_format_enum(self):
Season = self.Season
self.assertEqual('{}'.format(Season.SPRING),
'{}'.format(str(Season.SPRING)))
self.assertEqual( '{:}'.format(Season.SPRING),
'{:}'.format(str(Season.SPRING)))
self.assertEqual('{:20}'.format(Season.SPRING),
'{:20}'.format(str(Season.SPRING)))
self.assertEqual('{:^20}'.format(Season.SPRING),
'{:^20}'.format(str(Season.SPRING)))
self.assertEqual('{:>20}'.format(Season.SPRING),
'{:>20}'.format(str(Season.SPRING)))
self.assertEqual('{:<20}'.format(Season.SPRING),
'{:<20}'.format(str(Season.SPRING)))
def test_format_enum_custom(self):
class TestFloat(float, Enum):
one = 1.0
two = 2.0
def __format__(self, spec):
return 'TestFloat success!'
self.assertEqual('{}'.format(TestFloat.one), 'TestFloat success!')
def assertFormatIsValue(self, spec, member):
self.assertEqual(spec.format(member), spec.format(member.value))
def test_format_enum_date(self):
Holiday = self.Holiday
self.assertFormatIsValue('{}', Holiday.IDES_OF_MARCH)
self.assertFormatIsValue('{:}', Holiday.IDES_OF_MARCH)
self.assertFormatIsValue('{:20}', Holiday.IDES_OF_MARCH)
self.assertFormatIsValue('{:^20}', Holiday.IDES_OF_MARCH)
self.assertFormatIsValue('{:>20}', Holiday.IDES_OF_MARCH)
self.assertFormatIsValue('{:<20}', Holiday.IDES_OF_MARCH)
self.assertFormatIsValue('{:%Y %m}', Holiday.IDES_OF_MARCH)
self.assertFormatIsValue('{:%Y %m %M:00}', Holiday.IDES_OF_MARCH)
def test_format_enum_float(self):
Konstants = self.Konstants
self.assertFormatIsValue('{}', Konstants.TAU)
self.assertFormatIsValue('{:}', Konstants.TAU)
self.assertFormatIsValue('{:20}', Konstants.TAU)
self.assertFormatIsValue('{:^20}', Konstants.TAU)
self.assertFormatIsValue('{:>20}', Konstants.TAU)
self.assertFormatIsValue('{:<20}', Konstants.TAU)
self.assertFormatIsValue('{:n}', Konstants.TAU)
self.assertFormatIsValue('{:5.2}', Konstants.TAU)
self.assertFormatIsValue('{:f}', Konstants.TAU)
def test_format_enum_int(self):
Grades = self.Grades
self.assertFormatIsValue('{}', Grades.C)
self.assertFormatIsValue('{:}', Grades.C)
self.assertFormatIsValue('{:20}', Grades.C)
self.assertFormatIsValue('{:^20}', Grades.C)
self.assertFormatIsValue('{:>20}', Grades.C)
self.assertFormatIsValue('{:<20}', Grades.C)
self.assertFormatIsValue('{:+}', Grades.C)
self.assertFormatIsValue('{:08X}', Grades.C)
self.assertFormatIsValue('{:b}', Grades.C)
def test_format_enum_str(self):
Directional = self.Directional
self.assertFormatIsValue('{}', Directional.WEST)
self.assertFormatIsValue('{:}', Directional.WEST)
self.assertFormatIsValue('{:20}', Directional.WEST)
self.assertFormatIsValue('{:^20}', Directional.WEST)
self.assertFormatIsValue('{:>20}', Directional.WEST)
self.assertFormatIsValue('{:<20}', Directional.WEST)
def test_hash(self):
Season = self.Season
dates = {}
@ -232,7 +330,7 @@ class TestEnum(unittest.TestCase):
def test_floatenum_from_scratch(self):
class phy(float, Enum):
pi = 3.141596
pi = 3.1415926
tau = 2 * pi
self.assertTrue(phy.pi < phy.tau)
@ -240,7 +338,7 @@ class TestEnum(unittest.TestCase):
class FloatEnum(float, Enum):
pass
class phy(FloatEnum):
pi = 3.141596
pi = 3.1415926
tau = 2 * pi
self.assertTrue(phy.pi < phy.tau)