I also generally think of Enum as a collection of constants so I favor CAP_WORDS for enum members. I will admit that my answer is biased in that I don't typically create Enums that have a whole bunch of methods as you've done in your example. For your example code, I might separate it out into two classes (something representing a Date and an enum representing a Holidays). The former class could use the latter to compute things like "Next business day", etc.
On Mon, Jul 18, 2016 at 8:41 AM, Guido van Rossum guido@python.org wrote:
Honestly my own preference would be to use UPPER_CASE, emphasizing the const-ness. CapWords is really only used for classes, which are entirely different beasts. And lower_case is for methods and variables. I think it's useful to emphasize that an enum is neither.
On Mon, Jul 18, 2016 at 8:17 AM, Ethan Furman ethan@stoneleaf.us wrote:
There are currently a few locations in the stdlib, such as http and
socket,
that are now using Enums to replace constants; those names are all upper-case -- those
aren't
the names I am speaking of.
The names I am speaking of are those in brand-new enumerations where we
have
full control.
As an example:
class FederalHoliday(AutoNumberEnum): NewYear = "First day of the year.", 'absolute', JANUARY, 1 MartinLutherKingJr = "Birth of Civil Rights leader.", 'relative', JANUARY, MONDAY, 3 President = "Birth of George Washington", 'relative', FEBRUARY,
MONDAY,
3 Memorial = "Memory of fallen soldiers", 'relative', MAY, MONDAY, 5 Independence = "Declaration of Independence", 'absolute', JULY, 4 Labor = "American Labor Movement", 'relative', SEPTEMBER, MONDAY, 1 Columbus = "Americas discovered", 'relative', OCTOBER, MONDAY, 2 Veterans = "Recognition of Armed Forces service", 'relative',
NOVEMBER,
11, 1 Thanksgiving = "Day of Thanks", 'relative', NOVEMBER, THURSDAY, 4 Christmas = "Birth of Jesus Christ", 'absolute', DECEMBER, 25
def __init__(self, doc, type, month, day, occurance=None): self.__doc__ = doc self.type = type self.month = month self.day = day self.occurance = occurance def date(self, year): """ returns the observed date of the holiday for `year` """" ... @classmethod def next_business_day(cls, date, days=1): """ Return the next `days` business day from date. """ ... @classmethod def count_business_days(cls, date1, date2): """ Return the number of business days between 'date1' and 'date2'. """ ... @classmethod def year(cls, year): """ Return a list of the actual FederalHoliday dates for `year`. """ ...Take the name "NewYear": if it had been a global constant I would have named it "NEWYEAR"; if it had been a normal class attribute I would have named it "new_year"; however, being an Enum member, it is neither of those things.
<context switch> I've written some custom data types as part of my dbf package, and a few
of
them have instances that are singletons that are created in the global (okay, module)
namespace,
and for them I followed Python's lead in naming singletons: Python has used Title Case
in
such things as None, True, and False, so I followed suit and named mine -- Null, NullDate, NullTime, NullDateTime, etc. </context switch>
Given my past history with using and creating singleton objects, I
followed
suit when creating my own Enum classes.
I was recently queried about my apparent break with PEP 8 for naming Enum members, to which I replied:
Considering the strange beast that an Enum is, there is not much
precedent
for it anywhere.
Consider:
Enum is a class
but it is a container
and can be iterated over
and it has a length (which can be zero)
but it's always True in a boolean sense
Enum members are instances of the Enum class
but are pre-created
and new ones cannot be created
but are available as attributes on the class
Given all that I have been using Title case (or CamelCase) to name the members as it helps distinguish an Enum member from an ordinary attribute (which Enum
classes
can also have).
I forgot to include in that reply that I think CamelCase also helps to emphasize the special singleton nature of Enum members.
My question for the community: Your thoughts/opinions of my reasoning,
and
if you don't agree then which casing choice would you recommend and use, and why?
(Reminder:
this question does not include Enums whose names are replacements for existing constants
and so
the names cannot be changed.)
-- ~Ethan~ _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
-- --Guido van Rossum (python.org/~guido) _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/