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Let me use medical doctors to explain my question. Now doctors have different fields of specialization, like Neurologist=0,Oncologist=1,Cardiologist=2,Gynecologist=3 etc. Let's say I have a method that takes one of these specialities as an integer and uses it as a parameter to a stored procedure in a database:

DisplaySkills(int speciality)
{
   //create a connection to a database, refer to a stored procedure in the database;
   //send "speciality" as an argument to that stored procedure
}

Now, here I'm sort of in a dilemma as to whether I should have those specialities inside an enum or declare them seperately. From the first sight it feels like I should go with enums because it's just the case where "one thing can be one of several" but on the other hand it turns out that if I use enums, then I'll have to cast it to get its internal value. Here's an example:

enum Speciality
{
  Neurologist=0,
  Oncologist=1,
  Cardiologist=2,
  Gynecologist=3
}
.............
Speciality spec=Speciality.Oncologist;
.............
DisplaySkills(int(spec));

I don't know, maybe having to cast an enum is a perfectly normal practice and is widely used by programmers, but I thought it would impact the performance (no matter noticeably or not)

Mikayil Abdullayev
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4 Answers4

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I'd go with method DisplaySkills which accepts enum as parameter. Do casting only when call stored procedure.

Because when is see DisplaySkills(int speciality) then there is no connection with specialties declared in some enum. Maybe I should use it this way?

DisplaySkills(500);

On the other hand:

DisplaySkills(Speciality.Neurologist);

It tells me about all possible parameter values. Also I'd change name to DisplaySkillsOf(Speciality.Cardiologist) - looks more like English sentence then. And I'd added guard condition to check that passed value contained in Speciality enum. Otherwise somebody could do this 

DisplaySkills((Speciality)500);

And only inside this method you convert passed enum to int when creating parameter (looks like you are using ADO.NET) 

cmd.Parameters.Add(new SqlParameter("@Speciality", (int)spec));

One more tip about creating guard for your method. You can use generic enum wrapper to check if appropriate value was passed

if (!Enum<Speciality>.IsDefined(spec))
     throw new ArgumentException("spec");
Community
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Sergey Berezovskiy
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    I totally agree both about the leaving potential of passing any integer to the above method and amending the name to be more like English. – Mikayil Abdullayev Nov 15 '12 at 08:12
  • And also, what if want to have constants not as an integral type but as a string? Can enums still be used for this purpose or constants are the only way? – Mikayil Abdullayev Nov 15 '12 at 08:14
  • @MikeJM only integral numeric type could be used as enum values. But you can use name of enum constant later, or write a simple converter – Sergey Berezovskiy Nov 15 '12 at 08:20
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Should I use enums or just seperate constants where I'll need their internal values

In your case I'll choose enum over constant fields.

maybe having to cast an enum is a perfectly normal practice.

Yes. It is.

Azodious
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I suggest you to use enum instead of say, static constant class, simply because it is Type safe.
Rule of a thumb: if you have just Int + string value, use enum. If you have more fields, use static class.

RAS
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1

If you are worried about casting then let me tell you it isn't required here you could use this

int value = Speciality.Cardiologist.GetHashCode();
yogi
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