Enum Naming Convention - Plural

Microsoft recommends using singular for Enums unless the Enum represents bit fields (use the FlagsAttribute as well). See Enumeration Type Naming Conventions (a subset of Microsoft's Naming Guidelines).

To respond to your clarification, I see nothing wrong with either of the following:

public enum OrderStatus { Pending, Fulfilled, Error };

public class SomeClass { 
    public OrderStatus OrderStatus { get; set; }
}

or

public enum OrderStatus { Pending, Fulfilled, Error };

public class SomeClass {
    public OrderStatus Status { get; set; }
}

I started out naming enums in the plural but have since changed to singular. Just seems to make more sense in the context of where they're used.

enum Status { Unknown = 0, Incomplete, Ready }

Status myStatus = Status.Ready;

Compare to:

Statuses myStatus = Statuses.Ready;

I find the singular form to sound more natural in context. We are in agreement that when declaring the enum, which happens in one place, we're thinking "this is a group of whatevers", but when using it, presumably in many places, that we're thinking "this is one whatever".

The situation never really applies to plural.

An enum shows an attribute of something or another. I'll give an example:

enum Humour
{
  Irony,
  Sarcasm,
  Slapstick,
  Nothing
}

You can have one type, but try think of it in the multiple, rather than plural:

Humour.Irony | Humour.Sarcasm

Rather than

Humours { Irony, Sarcasm }

You have a sense of humour, you don't have a sense of humours.

In general, the best practice recommendation is singular, except for those enums that have the [Flags] attribute attached to them, (and which therefore can contain bit fields), which should be plural.

After reading your edited question, I get the feeling you may think the property name or variable name has to be different from the enum type name... It doesn't. The following is perfectly fine...

  public enum Status { New, Edited, Approved, Cancelled, Closed }

  public class Order
  {
      private Status stat;
      public Status Status
      { 
         get { return stat; }
         set { stat = value; }
      }
  }

This is one of the few places that I disagree with the convention enough to go against it. TBH, I HATE that the definition of an enum and the instance of it can have the same name. I postfix all of my Enums with "Enum" specifically because it makes it clear what the context of it is in any given usage. IMO it makes the code much more readable.

public enum PersonTypesEnum {
    smart,
    sad,
    funny,
    angry
}


public class Person {   
    public PersonTypesEnum PersonType {get; set;}
}

Nobody will ever confuse what is the enum and what is the instance of it.

Coming in a bit late...

There's an important difference between your question and the one you mention (which I asked ;-):

You put the enum definition out of the class, which allows you to have the same name for the enum and the property:

public enum EntityType { 
  Type1, Type2 
} 

public class SomeClass { 
  public EntityType EntityType {get; set;} // This is legal

}

In this case, I'd follow the MS guidelins and use a singular name for the enum (plural for flags). It's probaby the easiest solution.

My problem (in the other question) is when the enum is defined in the scope of the class, preventing the use of a property named exactly after the enum.

If you are trying to write straightforward, yet forbidden code like this:

    public class Person
    {
        public enum Gender
        {
            Male,
            Female
        }
        //Won't compile: auto-property has same name as enum
        public Gender Gender { get; set; }  
    }

Your options are:

Ignore the MS recommendation and use a prefix or suffix on the enum name: public class Person { public enum GenderEnum { Male, Female } public GenderEnum Gender { get; set; } } Move the enum definition outside the class, preferably into another class. Here is an easy solution to the above: public class Characteristics { public enum Gender { Male, Female } } public class Person { public Characteristics.Gender Gender { get; set; } }

Best Practice - use singular. You have a list of items that make up an Enum. Using an item in the list sounds strange when you say Versions.1_0. It makes more sense to say Version.1_0 since there is only one 1_0 Version.

On the other thread C# naming convention for enum and matching property someone pointed out what I think is a very good idea:

"I know my suggestion goes against the .NET Naming conventions, but I personally prefix enums with 'E' and enum flags with 'F' (similar to how we prefix Interfaces with 'I')."

The reason for using a plural for a enum declaration is the fact that ( at the time of declaration ) we declare it with multiple values, so plural seems good... But we ignore the fact that enum when declared specifies what value it can have ( from the given set of values ). It doesn't mean that the instance of that enum will store multiple values..... When we write: enum Days { MON, TUE, WED, THU, FRI, SAT, SUN}; We are making it plural because of the multiple values provide.. However when used (Days day = Days.MON; ) we completely ignore that instance of that enum is supposed to have a single value.... So when we write : enum Day { MON, TUE, WED, THU, FRI, SAT, SUN }; We mean that there is a enum that can have any one day as its value, so singular is more appropriate. Although (already described above ), to get around this without using singular names is by using any kind of Indicator, like DayEnum or EDay ( i prefer the second one)....