On 04/13/2016 12:12 PM, Antoon Pardon wrote:
I have been looking at the enum documentation and it
seems enums are missing two features I rather find
important.
1) Given an Enum value, someway to get the next/previous
one
2) Given two Enum values, iterate over the values between
them.
Did I miss those in the documentation or are they really
missing?
From the doc :
"While Enum and IntEnum are expected to cover the majority of use-cases,
they cannot cover them all. Here are recipes for some different types of
enumerations that can be used directly, or as examples for creating
one’s own."
I would disagree with you when you state that the features you mentioned
are important. They could be useful, in certain cases but most of your
code would better be agnostic to the enum value.
Now it is possible that you specifically work with a system where those
features would be really useful. As mentioned by the documentation,
subclassing Enum is possible:
tested with python 2.7
from enum import IntEnum
class UltimateEnum(IntEnum):
@classmethod
def range(cls, *args):
enumToVal = lambda e: e.value if isinstance(e, cls) else e
return (i for i in cls if i.value in range(*map(enumToVal,
args)))
@property
def next(self):
it = iter(self.__class__)
try:
for e in it:
if e is self: return next(it)
except StopIteration:
return None
return None
class Foo(UltimateEnum):
A = 1
B = 4
C = 9
D = 28
print "first to C:"
for f in Foo.range(Foo.C):
print f
print "B to D :"
for f in Foo.range(Foo.B, Foo.D):
print f
print "A to D+1 with step 2 : "
for f in Foo.range(Foo.A, Foo.D.value+1, 2):
print f
print "next property"
print Foo.A.next
print Foo.C.next
print Foo.D.next
In [1]: run test.py
first to C:
Foo.A
Foo.B
B to D :
Foo.B
Foo.C
A to D+1 with step 2 :
Foo.A
Foo.C
next property
Foo.B
Foo.D
None
Hope it helps,
jm
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