CODEWITHSUNDEEP
c#genericsenums
malber
malber

Reputation: 1073

Create list of enums and pass it to a method

I created a method which takes an enum and transforms it in a Dictionary where each int is associated with the name (as string) of the enum

// Define like this
public static Dictionary<int, string> getDictionaryFromEnum<T>()
{
   List<T> commandList = Enum.GetValues(typeof(T)).Cast<T>().ToList();
   Dictionary<int, string> finalList = new Dictionary<int, string>();
   foreach (T command in commandList)
   {
    finalList.Add((int)(object)command, command.ToString());
   }
 return finalList;
 }

(ps. yes, I have a double cast but the application is meant to be a very cheap-and-dirty C#-enum to Javascript-enum converter).

This can be easily used like this

private enum _myEnum1 { one = 1001, two = 1002 };
private enum _myEnum2 { one = 2001, two = 2002 };
// ... 
var a = getDictionaryFromEnum<_myEnum1>();
var b = getDictionaryFromEnum<_myEnum2>();

Now, I was wondering whether I could create a list of enums to use for a series of calls to iterate my calls.

This was in the original question: [Why can't I call this?]

What should I do to be able to create a call like this one?

List<Type> enumsToConvertList = new List<Type>();
enumsToConvertList.Add(typeof(_myEnum1));
enumsToConvertList.Add(typeof(_myEnum2));
// this'll be a loop
var a = getDictionaryFromEnum<enumsToConvertList.ElementAt(0)>();

Upvotes: 7

Views: 15191

Answers (5)

WeisserHund
WeisserHund

Reputation: 160

Here is an alternate method that takes the Enum as a generic and returns a dictionary of all the members

 public static Dictionary<int, string> ToDictionary<T>()
    {
        var type = typeof (T);
        if (!type.IsEnum) throw new ArgumentException("Only Enum types allowed");
        return Enum.GetValues(type).Cast<Enum>().ToDictionary(value => (int) Enum.Parse(type, value.ToString()), value => value.ToString());
    }

Upvotes: 1

MrFox
MrFox

Reputation: 5106

Convert to the type later on:

List<Type> enumsToConvertList = new List<Type>();
enumsToConvertList.Add(_myEnum1);
var a = getDictionaryFromEnum<typeof(enumsToConvertList.ElementAt(0))>();

Upvotes: 0

lc.
lc.

Reputation: 116448

In simple terms, the type parameters to a generic must be known at compile time.

You are trying to pass a runtime System.Type object as a generic type specifier, which is not possible.

As for what you're trying to accomplish, your method does not actually need to be generic, since you are always returning a Dictionary<int, string>. Try passing the Type as a parameter to the method instead, as @lazyberezovsky demonstrates.

Upvotes: 0

Sergey Berezovskiy
Sergey Berezovskiy

Reputation: 236208

You can't specify generic argument type at runtime (well, without reflection). So, simply create non-generic method, which accepts argument of Type type:

public static Dictionary<int, string> getDictionaryFromEnum(Type enumType)
{
    return Enum.GetValues(enumType).Cast<object>()
               .ToDictionary(x => (int)x, x => x.ToString());
}

Usage:

List<Type> enumsToConvertList = new List<Type>();
enumsToConvertList.Add(typeof(_myEnum1));
enumsToConvertList.Add(typeof(_myEnum2));

var a = getDictionaryFromEnum(enumsToConvertList[0]);

Upvotes: 7

Reed Copsey
Reed Copsey

Reputation: 564363

Why can't I call this?

In that case, you're passing in System.Type, which is different than the generic specifier, which is a compile time value.

Upvotes: 2

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