Singular or plural for enumerations?

Question

Do you use singular or plural for enumerations? I think i makes best sense with plural in the declaration

enum Weekdays
{
    Monday,
    Tuesday,
    Wednesday,
    Thursday,
    Friday,
    Saturday,
    Sunday
}

... but I think it makes more sense with singular when using the type, e.g.

Weekday firstDayOfWeek = Weekday.Monday;

I read a recommendation somewhere to use singular whit regular enums and plural with flags, but I would like to hear som more pros and cons.

Answer 1

In the .NET Framework, most "normal" enums (e.g. DayOfWeek) have singular names and flag enums (e.g. StringSplitOptions, BindingFlags) have plural names. It makes sense, since a value of a flag enum can represent multiple items but for a non-flag enum, it can only represent a single item.

Answer 2

One recommendation comes from the .NET Framework Design Guidelines, page 59-60:

Do use a singular type name for an enumeration, unless its values are bit fields.

public enum ConsoleColor {
  Black,
  Blue,
  Cyan,
  ...

Do use a plural type name for an enumeration with bit fields as values, also called a flags enum.

[Flags]
public enum ConsoleModifiers {
  Alt,
  Control,
  Shift
}

Answer 3

It's subjective and doesn't matter what you use, as long as you're consistent (personally I use singular as its a carry over from my Sql conventions)

Answer 4

In general, I consider an enum definition to be a type definition, with the values of the enum being the different values the type can have; therefore it gets a singular name:

enum Weekday { SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY };

enum CoffeeSize { SMALL, MEDIUM, LARGE };

Answer 5

Here it is straight from Microsoft:

http://msdn.microsoft.com/en-us/library/4x252001(VS.71).aspx

Use a singular name for most Enum types, but use a plural name for Enum types that are bit fields.

Answer 6

Microsoft recommends using a singular name for enumerations unless it uses the Flags attribute. And as taken from the Framework Design Guidelines book you should not suffix enumeration type names with Enum, Flags, etc. and you should not prefix enumeration values with an abbreviation or acronym as was common with VB enumerations back in the day.